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Role of Oxygen Vacancy Arrangement on the Formation of a Conductive Filament in a ZnO thin Film

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Chinese Physics Letters 2014年第5期31卷 157-160页

作者：赵晶董静雨赵旭陈伟 College of Physics Science and Information Engineering Hebei Normal University Shijiazhuang 050024 Key Laboratory of Advanced films of Hebei Province Shijiazhuang 050024 Department of Physics and Electrical Engineering Handan College Handan 056005

We perform first-principles calculations for ZnO thin films with oxygen vacancy defects. The densities of states, partial atomic densities of states, charge density differences and atomic populations are presented. We show that the SET process, i.e., from a high resistive state to a low resistive state, is attributable to the aggregation and regular arrangement of the oxygen vacancies, which causes the formation of conductive filaments and leads to the low resistive state of the system.

关键词： zinc oxide thin films NONVOLATILE random-access memory TRANSITION metals DENSITY functional theory DENSITY of states

Van der Pauw Hall Measurement on Intended Doped ZnO films for p-Type Conductivity

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Chinese Physics Letters 2010年第6期27卷 171-174页

作者： GUO Yang LIU Yao-Ping LI Jun-Qiang ZHANG Sheng-Li MEI Zeng-Xia DU Xiao-Long Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190

A Van der Pauw Hall measurement is performed on the intended doped ZnO films （Na doped ZnO） grown by using the molecular beam epitaxial method. All as-grown samples show n-type conductivity, whereas the annealed samples （annealing temperature 900℃） show ambiguous carrier conductivity type （n- and p-type） in the automatic Van der Pauw Hall measurement. A similar result has been observed in Li doped ZnO and in as-doped ZnO films by other groups before. However, by tracing the Hall voltage in the Van der Pauw Hall measurement, it is found that this alternative appearance of both n- and p-type conductivity is not intrinsic behavior of the intended doped ZnO films, but is due to the persistent photoconductivity effect in ZnO. The persistent photoconductivity effect would strongly affect the accurate determination of the carrier conductivity type of a highly resistive intended doped ZnO sample.

关键词： HALL effect zinc oxide thin films MOLECULAR beam epitaxy CRYSTAL growth ANNEALING of crystals TEMPERATURE effect PHOTOCONDUCTIVITY

MICROSTRUCTURE AND PROPERTIES OF ANNEALED ZnO thin films DEPOSITED BY MAGNETRON SPUTTERING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 177-183页

作者： J.Lee W.Gao Z.Li M.Hodgson A.Asadov J.Metson DepartmentofMechanicalEngineering TheUniversityofAucklandAuckland1004NewZealand DepartmentofChemicalandMaterialsEngineering TheUniversityofAucklandAuckland1004NewZealand DepartmentofChemistry TheUniversityofAucklandPrivateBag92019Auckland1004NewZealand

ZnO thin films were deposited on a glass substrate by dc (direct current) and rf (radio frequency) magnetron sputtering. Post-deposition annealing was performed in different atmospheres and at different temperatures. The correlation of the annealing conditions with the microstructure and properties of the ZnO films wer e investigated by ultraviolet-visible spectroscopy, X-ray diffraction, conductiv ity measurement and scanning electron microscopy. Only the strong 002 peak could be observed by X-ray diffraction. The post-deposition annealing of ZnO films wa s found to alter the film's microstructure and properties, including crystallini ty, porosity, grain size, internal stress level and resistivity. It was also fou nd that after annealing, the conductivity of poorly conductive samples often imp roved. However, annealing does not improve the conductivity of samples with high conductivity prior to annealing. The resistivity of as-grown films can be decre ased from 102 to 10-4Ω·cm after annealing in nitrogen. To explain the effects of annealing on the conductivity of ZnO, it is believed that annealing may alter the presence and distribution of oxygen defects, reduce the lattice stress, cau se diffusion, grain coarsening and recrystallization. Annealing will reduce the density of grain boundaries in less dense films, which may decrease the resistiv ity of the films. On the other hand, annealing may also increase the porosity of thin films, leading to an increase in resistivity.

关键词： zinc oxide thin films microstructure magnetron sputtering post-deposition annealing electrical conductivity

Modified textured surface MOCVD-ZnO:B transparent conductive layers for thinfilm solar cells

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Journal of Semiconductors 2014年第4期35卷 37-41页

作者：陈新亮闫聪博耿新华张德坤魏长春赵颖张晓丹 Institute of Photo-Electronic thin Film Devices and Technology Nankai University Tianjin Key Laboratory of Photo-Electronic thin Film Devices and Technology Nankai University Key Laboratory of Opto-Electronic Information Science and Technology for Ministry of Education NankaiUniversity

Modified textured surface boron-doped ZnO （ZnO：B） transparent conductive layers for thin-film solar cells were fabricated by low-pressure metal organic chemical vapor deposition （LP-MOCVD） on glass substrates. These modified textured surface ZnO：B thin films included two layers. The first ZnO：B layer, which has a pyramid- shaped texture, was deposited under conventional growth conditions, and the second layer, which has a sphere- like structure, at a relatively lower growth temperature. Typical bi-layer ZnO：B thin films exhibit a high electron mobility of 27.6 cm^2/（V.s） due to improved grain boundary states. For bi-layer ZnO：B, the haze value increases and the total transmittance decreases with the increasing film thickness of the second modification layer. When applied in hydrogenated microcrystalline silicon （μc-Si：H） thin-film solar cells, the modified textured surface ZnO：B layers present relatively higher conversion efficiency than conventional ZnO：B films.

关键词： zinc oxide thin films transparent conductive oxides MOCVD textured surface thin-film solar cells

Effect of Different Substrate Temperature on Phosphorus-Doped ZnO thin films Prepared by PLD on Sapphire Substrates

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Chinese Physics Letters 2009年第5期26卷 217-219页

作者：赵子文胡礼中张贺秋孙景昌边继明梁红伟霍炳至于东麒陈希付强 School of Physics and Optoelectronic Technology Dedian University of Technology Dalian 116024

Phosphorus-doped ZnO （ZnO：P） thin films are deposited on a c-plane sapphire in oxygen at 350℃, 450℃, 550℃ and 650℃, respectively, by pulsed laser deposition （PLD）, then all the ZnO：P samples are annealed at 650℃ in oxygen with a pressure of 1 × 10^5 Pa. X-ray diffraction measurements indicate that the crystalline quality of the ZnO：P thin films is improved with the increasing substrate temperature from 350℃ to 550℃. With a further increase of the deposition temperature, the crystalline quality of the ZnO：P sample is degraded. The measurements of low-temperature photoluminescence spectra demonstrate that the samples deposited at the substrate temperatures of 350℃ and 450℃ show a strong acceptor-bound exciton （A^0X） emission. The electrical properties of ZnO：P films strongly depend on the deposition temperature. The ZnO：P samples deposited at 350℃ and 450℃ exhibit p-type conductivity. The p-type ZnO：P film deposited at 450℃ shows a resistivity of 1.846Ω·cm and a relatively high hole concentration of 5.100 × 10^17 cm^-3 at room temperature.

关键词： SUBSTRATES (Materials science) TEMPERATURE effect PHOSPHORUS SEMICONDUCTOR doping zinc oxide thin films PULSED laser deposition SAPPHIRES thin films -- Electric properties