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Origin of the giant persistent photoconductivity in LaAlO_(3)/SrTiO_(3)heterostructures probed by noise spectroscopy

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Journal of Materials Science & Technology 2023年第6期137卷 152-158页

作者： Kitae Eom Jung-Woo Lee Gyeongmo Yang Youngmin Kim Jaeyoung Jeon Jieun Yeon Hyungwoo Lee School of Advanced Materials Science and Engineering Sungkyunkwan University(SKKU)Suwon 16419South Korea KIURI Institute Yonsei UniversitySeoul 03722South Korea Department of Physics Ajou UniversitySuwon 16499South Korea Department of Energy Systems Research Ajou UniversitySuwon 16499South Korea

LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room *** abnormally strong PPC has attracted immense research interest due to its possible applications in optically-tunable electronic *** its promise,the fundamental understanding of the PPC in the LAO/STO heterostructures is still ***,we report that the giant PPC origi-nates from the photo-induced valence change in oxygen vacancies near the LAO/STO *** spec-tral analysis of the photocurrent and the model-fitting study consistently show that the ionized oxygen vacancies near the interface are neutralized during the electron relaxation *** hinder the complete relaxation of the photoexcited electrons by the deeply-located oxygen vacancies and result in the strong *** change in the ionization state distribution of the oxygen vacancies is probed by the per-sistent noise behavior at the frequency between 1 kHz and 20 kHz *** results provide insight into the role of oxygen vacancies in influencing the internal charge distribution and triggering the PPC phenomena in complex oxide heterostructures.

关键词： persistent photoconductivity LaAlO_(3)/SrTiO_(3)heterostructures Two-dimensional electron gases Oxygen vacancies Low-frequency noise Spectral analyses

persistent photoconductivity in neutron irradiated GaN

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Journal of Semiconductors 2013年第9期34卷 32-34页

作者：张明兰杨瑞霞刘乃鑫王晓亮 College of Information Engineering Hebei University of Technology Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of Sciences Semiconductor Lighting R & D Center Institute of SemiconductorsChinese Academy of Sciences

Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent pho toconductivity （PPC） and low temperature photoluminescence （PL） measurements were carried out. Pronounced PPC was observed in the samples before and after neutron irradiation without the appearance of a yellow lumi- nescence （YL） band in the PL spectrum, suggesting that the origin of PPC and YL are not related. Moreover, PPC phenomenon was enhanced by neutron irradiation and quenched by the followed annealing process at 900 ℃. The possible origin of PPC is discussed.

关键词： GaN irradiation neutron persistent photoconductivity

persistent photoconductivity of amorphous Hg0.78Cd0.22Te：In films

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Journal of Semiconductors 2016年第10期37卷 38-42页

作者：余连杰苏玉辉史衍丽李雄军赵维艳马启太云见赵鹏 Kunming Institute of Physics Kunming 650223 China

The persistent photoconductivity（PPC） of amorphous Hg（0.78）Cd（0.22）Te. In films has been studied under illumination by super-bandgap light（a He–Ne laser, hv=1.96 eV, 30 mW/cm^2） and sub-bandgap light（1000 K Blackbody source, the largest photon energies h vp=0.42 eV, 8.9 mW/cm^2） in the range of 80–300 K. The persistent photoconductivity effect increases with increase in illumination intensity and illumination time. However,it decreases with increase in working temperature. The non-exponential decay of photoconductivity implies the presence of continuous distribution of defect states in amorphous Hg（0.78）Cd（0.22）Te. In films. These results indicate that the decay of photoconductivity is not governed by the carrier trapped in the intrinsic defects, but it may be due to light-induced defects under light illumination.

关键词： amorphous Hg0.78Cd0.22Te persistent photoconductivity light-induced effects

Interface terminal group regulated organic phototransistors with tunable persistent and switchable photoconductivity

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Science China Chemistry 2022年第12期65卷 2567-2575页

作者： Di Xue Yingying Zhang Weijie Gong Yao Yin Zi Wang Lizhen Huang Lifeng Chi Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials&DevicesSoochow UniversitySuzhou215123China Gusu Laboratory of Materials Suzhou215123China Macao Institute of Materials Science and Engineering(MIMSE) MUST-SUDA Joint Research Center for Advanced Functional MaterialsMacao University of Science and TechnologyTaipaMacao999078China

With both light detection and intrinsic amplification functions,organic phototransistors have demonstrated promising applications,including photodetection and *** achieve excellent photoresponse and superior photogain,a common and effective strategy is to modulate the trapping effect with the purpose of reducing recombination or prolonging the lifetime of the photogenerated charge ***,introducing trapping sites delicately is challenging and might sacrifice the response rate together with a typical persistent ***,we demonstrate a facile strategy for achieving high photo-responsive organic phototransistors with both persistent and switchable photoconductivity features via interface terminal group *** varying the terminate groups of self-assembled monolayer(SAMs)from the strong electron withdrawing group-F,neutral−CH_(3) to electron donating−NH_(2) on the dielectric surface,we realize both minority carrier trapping and majority carrier trapping in the organic phototransistor based on the C8-BTBT active *** electron withdrawing effect of F significantly enhances the minority carrier trapping process and yields a high photoresponsivity with a long-lasting persistent *** contrast,the electron donating group−NH_(2) with a distinct majority carrier trapping ability causes switchable photoconductivity so that the photocurrent can rise pronouncedly and fully decay along with light on/***,both cases can deliver high performance with photoresponsivities higher than 104 A W^(−1) together with a photosensitivity in the level of 107 and a detectivity of approximately 10^(15)–10^(16) *** a tunable,excellent photoresponse property enables the convenient exploration of organic phototransistors to satisfy different application requirements.

关键词： organic phototransistor surface modification trapping persistent photoconductivity

Suppression of persistent photoconductivity in high gain Ga_(2)O_(3) Schottky photodetectors

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Chinese Physics B 2021年第12期30卷 508-514页

作者：周海涛丛璐佳马剑钢李炳生徐海洋刘益春 Key Laboratory for UV-Emitting Materials and Technology of Ministry of Education Northeast Normal UniversityChangchun 130024China

The defect-related photoconductivity gain and persistent photoconductivity(PPC)observed in Ga_(2)O_(3)Schottky photodetectors lead to a contradiction between high responsivity and fast recovery *** this work,a metal-semiconductor-metal(MSM)Schottky photodetector,a unidirectional Schottky photodetector,and a photoconductor were constructed on Ga_(2)O_(3)*** MSM Schottky devices have high gain(>13)and high responsivity(>2.5 A/W)at 230-250 nm,as well as slow recovery speed caused by ***,applying a positive pulse voltage to the reverse-biased Ga_(2)O_(3)/Au Schottky junction can effectively suppress the PPC in the photodetector,while maintaining high *** mechanisms of gain and PPC do not strictly follow the interface trap trapping holes or the self-trapped holes models,which is attributed to the correlation with ionized oxygen vacancies in the Schottky *** positive pulse voltage modulates the width of the Schottky junction to help quickly neutralize electrons and ionized oxygen *** realization of suppression PPC functions and the establishment of physical models will facilitate the realization of high responsivity and fast response Schottky devices.

关键词： Ga_(2)O_(3)Schottky photodetector persistent photoconductivity high gain pulse voltage oxygen vacancy

Ultraviolet irradiation dosimeter based on persistent photoconductivity effect of ZnO

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Chinese Physics B 2020年第5期29卷 561-566页

作者：王朝骏杨珣臧金浩陈彦成林超男刘忠侠单崇新 Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Materials PhysicsMinistry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China Key Laboratory of Materials Physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China

It is essential to determine the accumulative ultraviolet(UV)irradiation over a period of time in some cases,such as monitoring UV irradiation to the skin,solar disinfection of water,photoresist exposure,*** colorimetric dosimeters,which use dyes'color change to monitor the amount of UV exposure,have been widely ***,the exposure data of these UV colorimetric dosimeters can hardly be converted to digital signals,limiting their *** this paper,a UV dosimeter has been proposed and demonstrated based on the persistent photoconductivity(PPC)in zinc oxide microwires(ZnO MWs).The PPC effect usually results in high photoconductivity gain but low response speed,which has been regarded as a disadvantage for ***,in this work,the unique characteristics of the PPC effect have been utilized to monitoring the accumulative *** demonstrate that the photocurrent in the ZnO MWs depends on the accumulative UV exposure due to the PPC effect,thus the photocurrent can be utilized to determine the UV *** dosimeter is immune to visible light and exhibits a photoconductive gain of 2654,and the relative error of the dosimeter is about 10%.This UV dosimeter with electrical output is reusable and convenient to integrate with other electronic devices and may also open a new application area for the PPC effect.

关键词： dosimetry persistent photoconductivity photodetectors ultraviolet

A systematic study of light dependency of persistentphotoconductivity in a-InGaZnO thin-film transistors

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Chinese Physics B 2020年第11期29卷 508-515页

作者：王雅兰王明湘张冬利王槐生 School of Electronic and Information Engineering Soochow UniversitySuzhou 215006China

persistent photoconductivity(PPC)effect and its light-intensity dependence of both enhancement and depletion(E-/D-)mode amorphous InGaZnO(a-IGZO)thin-film transistors(TFTs)are systematically *** of oxygen vacancy(V O)defects of E-mode TFTs is relatively small,in which formation of the photo-induced metastable defects is thermally activated,and the activation energy(E a)decreases continuously with increasing *** of V O defects of D-mode TFTs is much larger,in which the formation of photo-induced metastable defects is found to be spontaneous instead of thermally ***,for the first time it is found that a threshold dose of light-exposure is required to form fully developed photo-induced metastable *** low light-exposure below the threshold,only a low PPC barrier is formed and the PPC recovery is *** increasing the light-exposure to the threshold,the lattice relaxation of metal cations adjacent to the doubly ionized oxygen vacancies(V O^2+)is fully developed,and the PPC barrier increases to∼0.25 eV,which remains basically unchanged under higher *** on the density of V O defects in the channel and the condition of light illumination,a unified model of formation of photo-induced metastable defects in a-IGZO TFTs is proposed to explain the experimental observations.

关键词： amorphous indium-gallium-zinc oxide thin-film transistors persistent photoconductivity lightintensity