Co-reporter:J.W. Zhou, T.R. Li, D. Zhang, B. Ren, S.W. Zhang, J. Huang, J.M. Zhang, L. Wang, Y.C. Jiang, J. Gao, L.J. Wang
Vacuum 2017 Volume 135() pp:115-120
Publication Date(Web):January 2017
DOI:10.1016/j.vacuum.2016.10.034
•Abnormal bipolar resistive switching characteristics were observed in all Pt/Al/a-C:Fe/Au/Ti memory cells.•The resistive switching behavior is attributed to mutative Al3+ fraction at the Al/a-C:Fe interface.•The influences of the variation in Schottky barrier height near the Al interface were also discussed.Carbon-iron composite films with different thicknesses (50, 100 and 150 nm) were deposited by DC magnetron sputtering method using a composite target (Fe: 4 at%, C: 96 at%). The resistive switching behaviors of Pt/Al/a-C:Fe/Au/Ti structures with different a-C:Fe film thicknesses are investigated. Abnormal bipolar resistive switching characteristics were observed in all Pt/Al/a-C:Fe/Au/Ti memory cells. Considering the endurance and retention properties, the RRAM cell with 100 nm thick a-C:Fe film as the dielectric layer showed the best performance with on/off-resistance ratio ∼10, and retention time >104 s. Based on the results of the X-ray photoelectron spectroscopy depth profile, the resistive switching behavior is attributed to mutative Al3+ fraction at the Al/a-C:Fe interface and the migration of Au ions between two electrodes.
Co-reporter:Kaifeng Qin, Lunjuan Li, Jian Huang, Ke Tang, Xiaotian Zhang, Meng Cao, Yue Shen, Linjun Wang
Surface and Coatings Technology 2017 Volume 320(Volume 320) pp:
Publication Date(Web):25 June 2017
DOI:10.1016/j.surfcoat.2017.01.068
•The ZnTe/Si p-i-n heterojunctions were fabricated successfully.•The crystalline quality of ZnTe films was improved by annealing treatment.•The heterojunction with intrinsic layer showed a good rectifying behavior.•The leakage current and ideality factor decreased after annealing treatment.The ZnTe/Si p-i-n heterojunctions were fabricated successfully by using direct-current (DC) magnetron sputtering. The effects of an intrinsic ZnTe layer and annealing treatment on the properties of p-i-n heterojunctions were investigated. The results showed that the crystallinity of the ZnTe films was improved after annealing treatment. Structural analysis revealed that the ZnTe films were zinc blende and highly oriented along the (1 1 1) direction. The optical band-gap is 2.20 eV and 2.25 eV for p-ZnTe and i-ZnTe films. The heterojunction with an intrinsic layer and annealing treatment showed a good rectifying behavior.
Co-reporter:Fei Wu;Yanhao Yu;Huang Yang;Lazarus N. German;Zhenquan Li;Jianguo Chen;Weiguang Yang;Lu Huang;Weimin Shi;Xudong Wang
Advanced Materials 2017 Volume 29(Issue 28) pp:
Publication Date(Web):2017/07/01
DOI:10.1002/adma.201701432
Efficient charge separation and transportation are key factors that determine the photoelectrochemical (PEC) water-splitting efficiency. Here, a simultaneous enhancement of charge separation and hole transportation on the basis of ferroelectric polarization in TiO2–SrTiO3 core–shell nanowires (NWs) is reported. The SrTiO3 shell with controllable thicknesses generates a considerable spontaneous polarization, which effectively tunes the electrical band bending of TiO2. Combined with its intrinsically high charge mobility, the ferroelectric SrTiO3 thin shell significantly improves the charge-separation efficiency (ηseparation) with minimized influence on the hole-migration property of TiO2 photoelectrodes, leading to a drastically increased photocurrent density ( Jph). Specifically, the 10 nm-thick SrTiO3 shell yields the highest Jph and ηseparation of 1.43 mA cm−2 and 87.7% at 1.23 V versus reversible hydrogen electrode, respectively, corresponding to 83% and 79% improvements compared with those of pristine TiO2 NWs. The PEC performance can be further manipulated by thermal treatment, and the control of SrTiO3 film thicknesses and electric poling directions. This work suggests a material with combined ferroelectric and semiconducting features could be a promising solution for advancing PEC systems by concurrently promoting the charge-separation and hole-transportation properties.
Co-reporter:Kaifeng Qin, Huanhuan Ji, Jian Huang, Ke Tang, Yibin Shen, Xiaotian Zhang, Meng Cao, Jijun Zhang, Yue Shen, Linjun Wang
Surface and Coatings Technology 2017 Volume 320(Volume 320) pp:
Publication Date(Web):25 June 2017
DOI:10.1016/j.surfcoat.2016.12.027
•High quality CdZnTe films are deposited by close spaced-sublimation method.•Ohmic contacts are formed on polished CdZnTe films by inserting ZnTe:Cu interlayer.•The CTLM is used to reveal the contact performance of contacts on CdZnTe films.•Low contact resistivity of ~ 0.79 Ω·cm2 is obtained for Au/ZnTe:Cu/CdZnTe contacts.Polycrystalline CdZnTe films with thickness about 300 μm were deposited by close spaced-sublimation (CSS) method. The as-deposited CdZnTe samples were polished by mechanical polishing (MP) process. Cu-doped ZnTe films were sputtered by RF magnetron sputtering as an intermediate layer to improve the performance of Ohmic contact of Au electrodes to CdZnTe films. The effect of Cu-doped ZnTe intermediate layers on the electrical characteristics of Au/CdZnTe and Au/ZnTe:Cu/CdZnTe was investigated by the circular transmission line model (CTLM). The results indicate a good Ohmic contact of Au/ZnTe:Cu/CdZnTe with low contact resistivity of about 0.79 Ω·cm2.
Co-reporter:Yuelu Zhang, Linjun Wang, Run Xu, Jian Huang, Jun Tao, Hua Meng, Jijun Zhang, Jiahua Min
Applied Surface Science 2016 Volume 388(Part A) pp:589-592
Publication Date(Web):1 December 2016
DOI:10.1016/j.apsusc.2015.09.194
Highlights
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Graphene layer was spin-coated on CdZnTe to form Au/graphene/CdZnTe/FTO structure.
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Graphene layer can significantly improve the contact property of Au/CdZnTe.
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Graphene layer can obviously enhance UV photo-response of CdZnTe.
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Graphene is a potential buffer material for CdZnTe based high-energy detectors.
Co-reporter:Jun Tao, Haitao Xu, Yuelu Zhang, Huanhuan Ji, Run Xu, Jian Huang, Jijun Zhang, Xiaoyan Liang, Ke Tang, Linjun Wang
Applied Surface Science 2016 Volume 388(Part A) pp:180-184
Publication Date(Web):1 December 2016
DOI:10.1016/j.apsusc.2016.01.245
Highlights
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A peel-off approach is adopted to study the interface chemistry of CdZnTe films.
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A thick mixed interlayer above 84 nm is found at a low growth temperature of 200 °C.
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A reaction-limited model is suggested to explain the formation of mixed interlayer.
Co-reporter:Zhangmin Pan, Yiming Yang, Jian Huang, Bing Ren, Hongze Yu, Run Xu, Huanhuan Ji, Lin Wang, Linjun Wang
Applied Surface Science 2016 Volume 388(Part A) pp:392-395
Publication Date(Web):1 December 2016
DOI:10.1016/j.apsusc.2015.12.125
Highlights
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Boron (10B) oxide films were successfully grown using RF magnetron sputtering.
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Effects of oxygen partial pressure on the property of the films were studied.
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Substrates were covered with B-rich film and film surface was covered with B2O3.
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The growth mechanism of films in oxygen atmosphere was analyzed using XPS.
Co-reporter:Bing Ren, Jian Huang, Hongze Yu, Weichuan Yang, Lin Wang, Zhangmin Pan, Linjun Wang
Applied Surface Science 2016 Volume 388(Part A) pp:565-570
Publication Date(Web):1 December 2016
DOI:10.1016/j.apsusc.2015.10.067
Highlights
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(1 1 0)-diamond films were grown by microwave plasma chemical vapor deposition.
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The H content in hydrogenated diamond films was quantified by a novel technique.
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Pinning effect changes after annealing proved by X-ray photoelectron spectroscopy.
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The thermal stability was studied by reflection electron energy loss spectroscopy.
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H does not desorb from the surface of H-terminated diamond films until 950 °C.
Co-reporter:Huanhuan Ji, Jian Huang, Lin Wang, Junnan Wang, Jianming Lai, Run Xu, Jijun Zhang, Yue Shen, Jiahua Min, Linjun Wang, Yicheng Lu
Applied Surface Science 2016 Volume 388(Part A) pp:444-447
Publication Date(Web):1 December 2016
DOI:10.1016/j.apsusc.2015.11.237
Highlights
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Cd1−xMnxTe films were grown on FTO by close spaced sublimation method.
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As-grown films were etched by bromine followed by two separate annealing processes.
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Post-annealing on structure and properties of Cd1−xMnxTe films were investigated.
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BM/N2 post-annealing treatment is appropriate for preparation of Cd1−xMnxTe film.
Co-reporter:Bing Ren, Meng Cao, Qing Zhang, Jian Huang, Zhi Zhao, Xiang Jin, Chao Li, Yue Shen, Linjun Wang
Journal of Alloys and Compounds 2016 659() pp: 74-81
Publication Date(Web):25 February 2016
DOI:10.1016/j.jallcom.2015.11.030
•Ultra-long CdS nanowires with high quality were synthesized by solvothermal method.•The influences of reaction conditions on the PL property of CdS nanowires were thoroughly studied.•Low temperature PL properties reveal that CdS nanowires were as better as bulk CdS.CdS nanowires with controllable size, orientation, and morphology were synthesized on a large scale by a solvothermal method. The mechanism for the formation of CdS nanowires evolved from CdS spherical particles can be divided into a short-period solid–solid transformation process and a long-period ripening process. Near-band-emission without distinct split phenomenon was observed in the PL spectrum of CdS nanowires at 10 K. The best fit results based on Varshni empirical equation support our assignment of FX. Temperature dependent integrated peak intensity and linewidth of FX were analyzed by means of a two-step quenching process model and well fitted by Toyozawa's theory. All fitted results including thermal activation energy, LO-phonon energy were close to that observed in bulk CdS, indicating high quality of nanomaterial but also revealing its promising applications in photonics.
Co-reporter:Yuelu Zhang, Jian Huang, Jijun Zhang, Qun Mou, Yue Shen, Linjun Wang
Surface and Coatings Technology 2016 Volume 296() pp:104-107
Publication Date(Web):25 June 2016
DOI:10.1016/j.surfcoat.2016.04.036
•CdZnTe films were treated by Ar plasma etching process with various etching time.•The structure and surface roughness of the film was closely related to etching time.•The CdZnTe film with 5 min plasma etching showed lower dark-current.•CdZnTe films with 5 min plasma etching showed better photo-response to UV light.In this work, Ar plasma etching was performed to polycrystalline CdZnTe thick films grown from close-spaced sublimation method. The effect of Ar plasma etching time on the microstructure, optical and photoelectric properties of CdZnTe films were investigated by using AFM, XRD, UV–visible spectrophotometer and current-voltage characterization system. The results showed that proper plasma etching time can significantly improve the surface roughness and passivate the CdZnTe film surface, leading to less surface leakage current and higher photo-response of the Au/CdZnTe/FTO photo-conductive structure. Its photo-response sensitivity under 281 nm UV irradiation increases with one order of magnitude after 5 min' etching.
Co-reporter:Sheng Ge, Haitao Xu, Wenzhen Wang, Runan Cao, Yanglin Wu, Wenqiang Xu, Jiabin Zhu, Fei Xue, Feng Hong, Run Xu, Fei Xu, Linjun Wang, Jian Huang
Vacuum 2016 Volume 128() pp:91-98
Publication Date(Web):June 2016
DOI:10.1016/j.vacuum.2016.03.013
•High performance planar perovskite solar cell is prepared based on the compact TiO2 films grown by RF sputtering.•A high open circuit voltage of about 1.03 V can be obtained as compared to 0.92 V of solution based TiO2.•Nearly 100% coverage of perovskite film on sputtered TiO2 can be observed using the one step method.•The full coverage and the proper band alignment are two reasons responsible for the high open circuit voltage.The uniform and compact n-type TiO2 window layers were prepared by RF sputtering using a TiO2 ceramic target. A high open circuit voltage of about 1.03 V with the efficiency of 13.23% can be obtained as compared to 0.92 V of solution based TiO2. Nearly 100% coverage of perovskite film on sputtered TiO2 can be observed in the scanning electron microscopy images, obviously higher than 92% coverage on solution-based TiO2. The full coverage of perovskite and the proper band alignment between sputtered TiO2 and spiro-OMeTAD are two reasons responsible for the high open circuit voltage. The effects of annealing, growth temperature, sputtering target and thickness on performance of solar cell are also discussed.
Co-reporter:Shuwei Zhang, Jiawei Zhou, Dian Zhang, Bing Ren, Lin Wang, Jian Huang, Linjun Wang
Vacuum 2016 Volume 125() pp:189-191
Publication Date(Web):March 2016
DOI:10.1016/j.vacuum.2015.12.025
•We prepareα-C:Co films by DC magnetron sputtering technique using a composite target (Co:4 at%, C:96 at%).•Reliable and reproducible switching behaviors have been observed in the Al/α-C:Co/FTO structure memory cells.•The Al/α-C:Co/FTO structure memory cells show excellent performance with on/off ratio ∼25, and retention time >105 s.•The observed resistive switching effect is attributed to the formation/rupture of Co filaments in the film.Co-doped amorphous carbon films were prepared by direct current magnetron sputtering technique with a composite target (Co:4 at%, C:96 at%). Reliable and reproducible bipolar resistive switching behaviors were observed in Al/α-C:Co/FTO structure memory cells with an on/off ratio about 25, and retention time >105 s. The conduction mechanisms of LRS and HRS were supposed to be attributed to Ohmic behavior and the SCLC, respectively. The observed resistive switching phenomena might originate from the formation/rupture of metal filaments due to the diffusion of Co in the film under an electric field.
Co-reporter:Yanglin Wu, Haitao Xu, Huanhuan Ji, Jian Huang, Jijun Zhang, Zebo Fang, Ke Tang, Xiaoyan Liang, Run Xu, Linjun Wang
Vacuum 2016 Volume 132() pp:106-110
Publication Date(Web):October 2016
DOI:10.1016/j.vacuum.2016.07.037
•The CdZnTe films with Zn content as high as 0.42 are achieved.•A high sticking coefficient ratio of Zn to Cd is one of two key factors to obtain CdZnTe films with a high Zn content.•A high Zn vapor pressure under low growth pressure is another key factor to obtain CdZnTe films with a high Zn content.The Cd1-xZnxTe films with a high x value of about 0.42 were achieved by close-spaced sublimation (CSS) method using a pre-alloyed CdZnTe source on the basis of two critical growth factors. A relatively high growth temperature is one of two key factors to achieve high Zn content in CdZnTe films. The x value of Cd1-xZnxTe varies from 0.10 to 0.42 as the substrate temperature changes from 100 to 500 °C under the pressure of 10 Pa. Moreover, it can be inferred that the sticking coefficient ratio of Zn to Cd is about 2.5–4 times at 500 °C than that at 400 °C. The other factor, more importantly, is the growth pressure, which should be below 10 Pa, while a high pressure of above 1000 Pa generally adopted in the Cd1-xZnxTe films using the CSS method always leads to Cd1-xZnxTe films with a low x value. The sudden increase of Zn vapor pressure under a growth pressure lower than 10 Pa is responsible for a high Zn content in the Cd1-xZnxTe films.
Co-reporter:Yuelu Zhang, Jian Huang, Jijun Zhang, Qun Mou, Yue Shen, Linjun Wang
Surface and Coatings Technology 2016 Volume 307(Part B) pp:1158-1161
Publication Date(Web):15 December 2016
DOI:10.1016/j.surfcoat.2016.11.012
•CdZnTe films were treated by Ar plasma etching process with various etching time.•The structure and surface roughness of the film was closely related to etching time.•The CdZnTe film with 5 min plasma etching showed lower dark-current.•CdZnTe films with 5 min plasma etching showed better photo-response to UV light.In this work, Ar plasma etching was performed to polycrystalline CdZnTe thick films grown from close-spaced sublimation method. The effect of Ar plasma etching time on the microstructure, optical and photoelectric properties of CdZnTe films were investigated by using AFM, XRD, UV–visible spectrophotometer and current-voltage characterization system. The results showed that proper plasma etching time can significantly improve the surface roughness and passivate the CdZnTe film surface, leading to less surface leakage current and higher photo-response of the Au/CdZnTe/FTO photo-conductive structure. Its photo-response sensitivity under 281 nm UV irradiation increases with one order of magnitude after 5 min' etching.
Co-reporter:Lunjuan Li, Jian Huang, Weichuan Yang, Ke Tang, Bing Ren, Haitao Xu, Linjun Wang
Surface and Coatings Technology 2016 Volume 307(Part B) pp:1024-1028
Publication Date(Web):15 December 2016
DOI:10.1016/j.surfcoat.2016.08.005
•We prepared p-CuS/n-GaN heterojunction diodes successfully.•The crystalline quality of CuS films was improved after annealing treatment.•The diode showed good rectifying behavior with low leakage current after annealing.•The turn-on voltage of the diode was about 1.2 V.•The ideality factor of the diode decreased after annealing treatment.The p-CuS/n-GaN heterojunctions were fabricated successfully using RF magnetron sputtering. It was found that the properties of CuS films with annealing treatment were superior to non-annealed ones through various tests of SEM, XRD, Raman, EDS, and absorption spectrum. The optical band-gap slightly increased after annealing treatment. The current-voltage (I–V) characteristics of p-CuS/n-GaN heterojunction were measured and showed well-defined rectifying behavior for the annealed device.
Co-reporter:Bing Ren, Lin Wang, Jian Huang, Ke Tang, Yimin Yang, Linjun Wang
Vacuum 2015 Volume 112() pp:70-72
Publication Date(Web):February 2015
DOI:10.1016/j.vacuum.2014.11.018
•CuS-Cu1.8S mixed phase films were grown on quartz by sputtering technique.•As-deposited films exhibit free-carrier absorption in the near infrared (NIR) region.•Metal-semiconductor transition (MST) were observed in as-deposited CuxS thin films.•To the best of our knowledge, it is the first time to report an MST in CuxS films.•MST phenomena observed are attributed to a phase transition from Cu1.8S to CuS.We report the semiconducting behavior at room temperature and a metal-semiconductor transition (MST) at lower temperature in copper sulfides (CuxS) thin films. CuxS thin films, deposited by direct magnetron sputtering technique, are found to be of CuS-Cu1.8S mixed phase by XRD. The deposited films exhibit low electrical resistivity close to ∼10−4 Ω cm at room temperature and free-carrier absorption in the near infrared (NIR) region due to excess holes in the valence band. Temperature dependent resistivity measurements show the MST at ∼260 K, to the best of our knowledge, for the first time. The temperature dependent metal-semiconductor transition is attributed to the phase transition from Cu1.8S to CuS at Tc during the cooling process. This work could help give insight into the transport characteristics as well as phase transition at lower temperature in copper sulfides thin films.
Co-reporter:Jiahua Min, Hui Li, Linjun Wang, Jijun Zhang, Xiaoyan Liang, Weiwei Liu, Xiaoxiang Sun, Dong Wang, Zhengwen Yuan, Gaoli Wei, Kaifeng Qin, Yiben Xia
Surface and Coatings Technology 2013 Volume 228(Supplement 1) pp:S97-S100
Publication Date(Web):15 August 2013
DOI:10.1016/j.surfcoat.2012.07.082
This paper investigates the hydrogen plasma treatment effects on the interface of Au/CdZnTe contact. Hydrogen plasma with high energy is the smallest and lightest atomic mass, which is easy to enter into the crystal surface to fill the vacancy defects. The Au/CdZnTe samples were treated by the microwave hydrogen plasma with the power of 60 W (average power density of 0.5 W/cm2) and the frequency of 13.6 MHz under different treatment times. Scanning electron microscope (SEM), current–voltage (I–V) and adhesion strength measurement were performed to analyze the interface properties of Au/CdZnTe before and after the hydrogen plasma treatment. The results show that the hydrogen plasma treatment can reduce the surface leakage current, decrease the point defects and improve the performance of the electrode contacts.Highlights► The Au/CZT samples were treated by the microwave hydrogen plasma. ► The hydrogen plasma treatment of Au/CZT for 4–8 min improved the contact performance. ► After the hydrogen plasma treatment over 16 min, the properties of Au/CZT grow worse.
Co-reporter:Jian Huang, Linjun Wang, Ke Tang, Meiai Lin, Yingzhou Yu, Xionggang Lu, Yiben Xia
Surface and Coatings Technology 2013 Volume 228(Supplement 1) pp:S397-S400
Publication Date(Web):15 August 2013
DOI:10.1016/j.surfcoat.2012.05.061
Boron-doped p-type diamond films were prepared by microwave-plasma chemical vapor deposition (MPCVD) method. Transparent ZnS/diamond film heterojunction diodes were fabricated by depositing n-type ZnS films on the p-type diamond substrates using radio-frequency (RF) magnetron sputtering method for the first time. Current–voltage (I–V) characteristics of the devices were examined, and the results showed the distinct rectifying characteristics with a turn-on voltage of about 1.1 V. The diode possessed an optical transmission of 50–70% from 500 nm to 800 nm wavelength region.Highlights► We prepare transparent n-ZnS/p-diamond heterojunction diodes. ► The diode shows rectifying behavior with turn-on voltage of ~ 1.1 V. ► The current transport mechanism depends on applied bias voltages. ► The diode has a broad transparent band from 500 nm to 800 nm region.
Co-reporter:Ke Tang, Linjun Wang, Jian Huang, Bin Ren, Qinkai Zeng, Kaifeng Qin, Lingyun Shi, Yiben Xia
Surface and Coatings Technology 2013 Volume 228(Supplement 1) pp:S401-S403
Publication Date(Web):15 August 2013
DOI:10.1016/j.surfcoat.2012.05.059
High quality freestanding diamond (FSD) films with smooth nucleation surfaces were grown by microwave plasma chemical vapor deposition (MPCVD) method. A p-type hydrogenated surface conductivity of FSD film was obtained by using hydrogen plasma treatment. The annealing process in vacuum on the p-type behavior of FSD nucleation surfaces was investigated by Hall effect measurement. H-terminated diamond phototransistors were fabricated and the results suggest that they may be ideally suited for ultraviolet (UV) switching applications.Highlights► We prepare freestanding diamond films with H-terminated p-type surface. ► We study the effect of annealing in vacuum on p-type behavior of diamond. ► The electrical properties keep stable after annealing below 600 °C. ► We fabricate an H-terminated diamond phototransistor. ► The device channel current is enhanced after illuminating with UV light.
Co-reporter:Xiaoyu Pan, Linjun Wang, Qingkai Zeng, Lingyun Shi, Run Xu, Jian Huang, Ke Tang, Yiben Xia
Surface and Coatings Technology 2013 Volume 228(Supplement 1) pp:S446-S448
Publication Date(Web):15 August 2013
DOI:10.1016/j.surfcoat.2012.05.032
In many electronic applications, the surface properties of hydrogen-terminated diamond films determine the eventual performance of the electronic device. In this work, diamond films were grown by hot-filament chemical vapor deposition method and hydrogenated films were obtained by hydrogen plasma treatment. X-ray photoelectron spectroscopy analysis was carried out to evaluate the film surface after annealing treatment. The C1s XPS spectrum showed the C1s spectrum changed after annealing treatment. In air atmosphere, hydrogen decreased and oxygen absorption increased. The interaction on the surface changed drastically after annealed in argon atmosphere and phase transition would happen when the annealing temperature increased to 600 °C.Highlights► We prepare diamond films by HFCVD and hydrogenate them by hydrogen plasma treatment. ► The XPS spectrum shows the C1s spectrum of films changed after annealing treatment. ► Hydrogen decreases and oxygen adsorption increases after annealed in air. ► The interaction on the surface changes drastically after annealed in argon. ► Phase transition may happen when the annealing temperature increases to 600 °C.
Co-reporter:Qingkai Zeng, Linjun Wang, Lingyun Shi, Kaifeng Qin, Jian Huang, Ke Tang, Jiahua Min, Weimin Shi, Yiben Xia
Surface and Coatings Technology 2013 Volume 228(Supplement 1) pp:S379-S381
Publication Date(Web):15 August 2013
DOI:10.1016/j.surfcoat.2012.05.097
(110)-oriented diamond films were grown by hot-filament chemical vapor deposition method. Microwave assisted hydrogen plasma etching process was used to obtain hydrogen-terminated diamond films. The influence of gas pressure and substrate temperature during hydrogen plasma etching on structural and electrical properties of diamond film was investigated. The ultra-violet Raman spectra showed CHX bond increased with the gas pressure and the substrate temperature. The Hall Effect measurement results showed that the higher CHX bond density led to a higher sheet carrier density and lower sheet resistance, which was helpful for the fabrication of high-frequency and high-power field-effect transistors.Highlights► We prepare (110)-textured diamond films by hot-filament CVD method. ► We use microwave plasma system to obtain hydrogen-terminated surface sample. ► We investigate the influence of parameter during plasma etching. ► The UV Raman show CHx bond increased with gas pressure and substrate temperature. ► Hall measurement show higher CHx bond density led to higher sheet carrier density.
Co-reporter:Liangmin Cai, Linjun Wang, Jian Huang, Beiling Yao, Ke Tang, Jijun Zhang, Kaifeng Qin, Jiahua Min, Yiben Xia
Vacuum 2013 Volume 88() pp:28-31
Publication Date(Web):February 2013
DOI:10.1016/j.vacuum.2012.08.009
High resistivity (3 × 109 Ω cm) polycrystalline CdZnTe thick films with thickness of 25 μm–150 μm were grown on SnO2: F-coated glass substrates by close-spaced sublimation method. The properties of polycrystalline CdZnTe films were studied by XRD, SEM and EDS, respectively. A CdZnTe film Schottky diode detector was also fabricated and investigated using current–voltage and capacitance–voltage methods. The photo-current density of the device was about 1508.69 nA/mm2 under light illumination (λ = 260 nm), at an applied negative voltage of 15 V. The results showed that polycrystalline CdZnTe thick film was suitable for application in ultraviolet detectors.Highlights► The preferred (111) oriented polycrystalline CdZnTe films were grown by CSS. ► CdZnTe films of thickness 25 μm–150 μm and high resistivity were obtained. ► Schottky diode was designed to investigate the electronic properties. ► I–V and C–V methods were carried out to evaluate the Schottky diode. ► A high photo-current density was obtained about 1580.69 nA/mm2.
Co-reporter:Kaifeng Qin, Linjun Wang, Jijun Zhang, Jiahua Min, Jian Huang, Xiaoyan Liang, Ke Tang, Yiben Xia
Vacuum 2012 Volume 86(Issue 7) pp:827-829
Publication Date(Web):8 February 2012
DOI:10.1016/j.vacuum.2011.01.021
The method of the electrode deposition process plays a vital role in determining the contact characteristics, which is often one of the dominant factors influencing the CdZnTe detector performance. In this work, a modified deposition process named two-step process for the electrode fabrication of CdZnTe detectors, was developed. This deposition process can dramatically increase the adhesion strength and reduce the inhomogeneity of the metal/semiconductor interface, and improve the detection ability of high energy radiation such as X-rays and gamma-rays. Scanning acoustic microscopy, shear tests, current–voltage test and energy spectra characteristics measurements were carried out in this work.Highlights► Two-step process for the electrode fabrication of CdZnTe detectors was developed. ► Two-step process can dramatically increase the adhesion strength and reduce the inhomogeneity of the metal/semiconductor interface. ► Two-step process can improve the detection ability of X-rays and gamma-rays.
Co-reporter:Kaifeng Qin, Linjun Wang, Jiahua Min, Jijun Zhang, Jian Huang, Xiaoyan Liang, Ke Tang, Yiben Xia
Vacuum 2012 Volume 86(Issue 7) pp:943-945
Publication Date(Web):8 February 2012
DOI:10.1016/j.vacuum.2011.07.048
The characteristics of the Au contacts deposited by three different processes before and after accelerating aging tests have been investigated in this paper. The experimental results indicate that the aging tests can cause the degradation of the contact interfacial properties, such as continuities, adhesion strength and ohmic characteristics, especially for the contact electrode deposited by the thermal vacuum evaporation, which would influence the performance of CdZnTe detectors.Highlights► Au contacts on CdZnTe wafers formed by electroless deposition, sputtering and thermal vacuum evaporation were investigated. ► Aging tests could cause the degradation of contact interfacial properties. ► SAM, I-V and aging test indicated the degradation was serious for CdZnTe detector with Au evaporated electrode.
Co-reporter:Linjun Wang, Qingkai Zeng, Jian Huang, Run Xu, Ke Tang, Jijun Zhang, Yiben Xia
Thin Solid Films 2011 Volume 520(Issue 2) pp:717-720
Publication Date(Web):1 November 2011
DOI:10.1016/j.tsf.2011.04.160
In this work, we developed X-ray radiation detectors with sandwich structure fabricated from nano-crystalline diamond (NCD) films. These NCD films with different grain size ranging from 15 nm to 160 nm were grown on silicon substrates using a hot-filament chemical vapor deposition technique. I–V measurement results indicate that with reducing of the grain size, the resistivity of diamond films decreases from 9.5 × 108 to 6.20 × 107 Ω cm and the ratio of the photocurrent to the dark-current (Iph/Id) of the detectors decreases rapidly from 0.45 to 0.09 at an electric field of 50 kV/cm. Typical spectral response to 5.9 keV 55Fe X-rays shows that counting efficiency and energy resolution of NCD detectors with large grains are better than those of detectors with small grains, due to the less defects and grain-boundaries contained in the film.
Co-reporter:Yuelu Zhang, Linjun Wang, Run Xu, Jian Huang, Hua Meng, Jun Tao, Jijun Zhang, Jiahua Min, Yue Shen
Journal of Crystal Growth (1 December 2015) Volume 431() pp:10-14
Publication Date(Web):1 December 2015
DOI:10.1016/j.jcrysgro.2015.08.024
•Effects of post-treatment on electrical property of CdZnTe films were studied.•The mobility–lifetime product of CdZnTe film was reported for the first time.•Surface UV sensitivity distribution of CdZnTe was reported for the first time.•ZnCl2 annealing process has not improved the electrical property of CdZnTe surface.Polycrystalline CdZnTe thick films with an average grain size of 30 μm and thickness of 270 μm were successfully grown on SnO2:F (FTO)-coated glass substrates by close-spaced sublimation method. Electrical properties and UV response of CdZnTe thick films after Br–MeOH etching and ZnCl2 annealing treatment were investigated. By means of the photo-current measurements, the value of mobility–lifetime (μτ) products for CdZnTe films were firstly reported. The results showed that Br–MeOH etching significantly improved UV detection sensitivity of CdZnTe thick films, and made the surface distribution of UV sensitivity more homogeneous. It was also found that a ZnCl2 annealing process did not improve the electrical properties.
