Surface photovoltage characterizations of Si nanopillar arrays for verifying field-effect passivation using a SiNx layer

Eunah Kim,Yunae Cho,Ah-rum Sohn,김동욱,박형호,김준동 한국물리학회 2016 Current Applied Physics Vol.16 No.2

The surface photovoltage (SPV) characteristics of periodic nanopillar (NP) arrays formed on Si wafers were investigated. The NP arrays exhibited broadband omnidirectional antireflection effects with Mie resonance. Kelvin probe force microscopy (KPFM) revealed that the positive fixed charges in SiNx layers induced band bending at the Si surface and increased surface photovoltage (SPV) at the NP top surface. Estimated SPV values, determined by the amount of surface band bending, were similar in NPs and planar counterparts. This finding suggests that field effect passivation by the dielectric layer coating could help improve photovoltaic performance of nanostructure-based Si solar cells and that KPFM may be a useful tool for the investigation of surface electrical properties of Si nanostructures.

Interaction and surface photovoltage effect of MoS2 with Na deposition

Lee Wonhui,Lee Sangsoo,Lee Geunseop 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.84 No.5

Using photoelectron spectroscopy (PES) with synchrotron radiation (SR), we investigated the interaction of a MoS2 surface with Na. When Na was deposited at room temperature and at low temperature (~ 90 K), the PES data showed that both the core levels and the valence band shifted toward high binding by almost the same energies, compared with the pristine surface. This indicates that the deposited Na interacted non-reactively with MoS2, while inducing a rigid shift of the PES peaks by donating electrons to the MoS2 substrate. Deposition of sufcient amount of Na allowed the conduction band of MoS2 to be partially flled, revealing a clear Fermi edge. For Na deposition at low temperature, the Fermi edge appeared above the reference Fermi level. We attribute this to the surface photovoltage (SPV) efect generated by SR light. The SPV was measured to decrease when the sample was heated, refecting the increasing recombination of SR-generating electron–hole pairs with increasing temperature.

${In_{0.5}}({Ga_{1-x}}{Al_x})_{0.5}P$/GaAs 이중 이종접합 구조에 대한 표면 광전압 특성

김기홍,최상수,배인호,김인수,박성배,Kim, Ki-Hong,Choi, Sang-Soo,Bae, In-Ho,Kim, I n-Soo,Park, Sung-Bae 한국재료학회 2001 한국재료학회지 Vol.11 No.8

Surface photovoltage spectroscopy was used to study $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P/GaAs$ grown by metalorganic chemical vapor deposition(MOCVD). Energy gap related transition in GaAs and $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P$ were observed. By measuring the frequency dependence of $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P/GaAs$, we observed that SPV line shape does not chance, whereas the amplitude change. This results is due to the difference in the lifetimes of the photocarriers in GaAs and in $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P$. We also have evaluated the parameters that describe the temperature dependences of the band gap. Metalorganic chemical vapor deposition (MOCVD)으로 성장한 $In_{0.5}$ ($Gal_{1-x}$ $Al_{x}$ )0.5P/GaAS 이중 이종접합 구조의 특성을 표면 광전압 (surface Photovoltage ; SPV) 측정으로 연구하였다. $In_{0.5}$($Gal_{1-x}$ $Al_{x}$ )0.5P/GaAS 이중 이종접합 구조의 SPV 측정값을 Lorentzian 피팅한 띠 간격에너지 ($E_{0}$ ) 값과 조성비 (x)로 구한 이론 값이 잘 일치하였다. 그리고 변조 주파수 의존성을 측정한 결과 SPV 신호의 형태는 변하지 않고, 신호의 크기만이 변하는 것은 광 조사에 따른 전기적 상태의 과도 현상에 따른 것이고, GaAs와 InGaAlP의 특성시간의 차이는 광 캐리어의 수명의 차이로 분석된다. 그리고 온도 의존성 측정으로 $In_{0.5}$ /($Gal_{1-x}$ $Al_{x}$ )0.5P/GaAS 이중 이종 접합 시료의 균일한 변형분포와 계면상태가 양호함을 알 수 있었다.

Communication—In-Line Detection of Silicon Surface Quality Variation Using Surface Photovoltage and Room Temperature Photoluminescence Measurements

Kim, Jae Hyun,Han, Seung Min,Yoo, Woo Sik The Electrochemical Society 2016 ECS journal of solid state science and technology Vol.5 No.7

<P>Occasionally, in volume device manufacturing, a large number of particles may be generated on cleaned Si wafers. Surface (ionic, organic and/or metallic) contamination is generally suspected. However, conventional chemical analysis techniques for contamination are generally not able to distinguish between Siwafers with good and poor particle performance. Nosuspicious chemicals and elements were detected from any wafers regardless of characterization techniques. Surface photovoltage (SPV) measurement barely showed the differences between wafers with good and poor particle performance. Multiwavelength room temperature photoluminescence (RTPL) showed significant differences in intensity between them, indicating the presence of surface quality variations. (C) The Author(s) 2016. Published by ECS. All rights reserved.</P>

Surface photovoltage spectroscopy study of InAs quantum dot in quantum well multilayer structures for infrared photodetectors

Donchev, V.,Ivanov, Ts.,Ivanova, Ts.,Mathews, S.,Kim, J.O.,Krishna, S. Academic Press 2015 Superlattices and microstructures Vol.88 No.-

Inter-band optical transitions in InAs submonolayer and Stranski-Krastanov quantum dot (QD) in quantum well (QW) nanostructures are studied by means of room temperature surface photovoltage (SPV) spectroscopy taking advantage of its high sensitivity and contactless nature. The QD optical transitions are identified by the combined analysis of SPV amplitude and phase spectra and are in agreement with photoluminescence results. The SPV spectra have further revealed the optical transitions in all other relevant layers in the structures - wetting layer, QWs, and AlGaAs barriers. The analysis of the SPV phase spectra has revealed that the carrier separation and transport in the QD structure is determined by the energy band bending, resulting from the slight residual p-type doping. The complicated interaction between the SPV signals from the nanostructure and the semi-insulating GaAs substrate is discussed and clarified. The advantages of the SPV spectroscopy for characterizing complicated nanostructures at room temperature are highlighted.

표면 광전압 방법에 의한 ${Al_{0.24}}{Ga_{0.76}}As/GaAs$ 다중 양자우물 구조의 광 흡수 특성

김기홍,최상수,손영호,배인호,황도원,신영남,Kim, Gi-Hong,Choe, Sang-Su,Son, Yeong-Ho,Bae, In-Ho,Hwang, Do-Won,Sin, Yeong-Nam 한국재료학회 2000 한국재료학회지 Vol.10 No.10

$Al_{0.24}Ga_{0.76}As/GaAs$ 다중 양자우물 구조의 고아 흡수 특성을 표면 광전압 방법을 사용하여 연구하였다. SPV 측정결과 1.42eV 부근에서 두 개의 신호가 나탔으며, 이는 화학적 에칭으로 GaAs 기판의 신호와 GaAs 완충층과 관련된 신호임을 확인 할 수 있었다. $Al_{0.24}Ga_{0.76}As$와 관련된 전이 에너지를 관찰하고, Kuech 등이 제안한 조성식을 이용하여 Al 조성(x=24%)을 결정하였다. 그리고 다중 양자우물에서 나타나는 전이 에너지 값들은 envelope-weve function approximation(EFA)로 계산한 이론치와 잘 일치하였다. 입사광의 세기에 따라 광 전압이 선형적으로 변한다는 것을 알 수 있었고, 온도가 감소함에 따른 전이 에너지의 변화를 관찰하였다. The characteristics of optical absorption in $Al_{0.24}Ga_{0.76}As/GaAs$ multi-quantum wells(MQWs) structure were investigated by using the surface photovoltage(SPV). The Spy features near 1.42 eV showed two overlapping signals. By chemical etching, we found associated with the GaAs substrate and the GaAs cap layer. The Al composition(x=24 %) was determined by Kuech's composition formula. In order to identify the transition energies. the experimentally observed energies were compared with results of the envelope function approximation for a rectangular quantum wells An amplitude variation of the relative Spy intensity from the GaAs substrate, llH, and llL was observed at different light intensities. A variation in the SPY line shape of the transition energies were observed with decreasing tempera­t ture.

Ultrasonically sprayed-on perovskite solar cells-effects of organic cation on defect formation of CH3NH3PbI3 films

Nakorn Henjongchom,Nopporn Rujisamphan,Pisist Kumnorkaew,I-Ming Tang,Vittaya Amornkitbumrung,Thidarat Supasai 한국물리학회 2019 Current Applied Physics Vol.19 No.12

Methylammonium lead iodide (CH3NH3PbI3) based perovskite having low degrees of the disorder is of great interest for optoelectronic and photovoltaic applications. In this work, a layer of CH3NH3PbI3 was successfully prepared using an ultrasonically sprayed-nebulous method. Changes in structural and optical properties alongside with photo-induced charge separation and transportation behavior were systematically studied. The surface photovoltage spectra reveal a significant reduction of the density of deep defect states as the organic content was increased. It was observed that the measured values of Urbach energies decrease from 33.36 to 28.24 meV as the amount of organic content was increased to an optimum value. The best perovskite solar cells obtained using the sprayed-on approach exhibited a Jsc of 16.54 mA/cm2, a Voc of 0.99 V, and a FF of 62.4, resulting in an overall PCE of 10.09%.

Photoelectrochemical and Charge Transfer Properties of SnS/TiO2 Heterostructure Nanotube Arrays

Yongfang Jia,Feng Yang,Fanggong Cai,Cuihua Cheng,Yong Zhao 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.3

SnS/TiO2 heterostructure nanotube arrays (NTAs) were synthesized through a successive ionic layer adsorption and reaction process. The photoelectrochemical (PEC) property of SnS/TiO2 heterostructure NTAs was evaluated in liquid junction PEC solar cells. The results revealed that SnS/TiO2 heterostructure NTAs exhibited PEC property with an open-circuit voltage of 1.08 V, a short-circuit current density of 1.55 mA/cm2, and a conversion efficiency of 0.75% under 1 sun illumination. These values are higher than those of pristine SnS nanoparticles and TiO2 NTAs. Surface photovoltage spectroscopy and phase spectroscopy measurements were conducted to verify the formation of heterojunction and probe charge transfer between SnS and TiO2NTAs. The PEC property and surface photovoltaic response enhancement of SnS/TiO2 heterostructure NTAs can be attributed to the enhanced electron-hole separation due to the effect of interfacial electric field in SnS/TiO2 heterostructure NTAs.

Optical Characterization of Zn0.95-xBe0.05MnxSe Mixed Crystals

H. P. Hsu,T. W. Chang,Y. S. Huang,F. Firszt,S. Legowski,H. Meczynsk,A. Marasek,K. Strza lkowski,K. K. Tiong,M. Munoz 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

Temperature-dependent photoluminescence (PL), contactless electrore ectance (CER) and surface photovoltage spectroscopy (SPS) characterizations of two Zn0.95-xBe0.05MnxSe mixed crystals with Mn contents x=0.05 and 0.20 grown by using the modified high-pressure Bridgman method has been carried out in the temperature range of 15-300 K. A typical PL spectrum at low temperature consists of a free exciton line, an edge emission due to recombenation of shallow donor-acceptor pairs and Mn2+-related intra-ionnic emissions. Te near band edge transition energies are determined lines in the PL spectra correspond quite well to the energies of the fundamental trasitions determinde from CER and SPS data. The parameters that descrbe the temperature dependence of the trasition energy of the fundamental band-edge excton are evaluated and discussed. Temperature-dependent photoluminescence (PL), contactless electrore ectance (CER) and surface photovoltage spectroscopy (SPS) characterizations of two Zn0.95-xBe0.05MnxSe mixed crystals with Mn contents x=0.05 and 0.20 grown by using the modified high-pressure Bridgman method has been carried out in the temperature range of 15-300 K. A typical PL spectrum at low temperature consists of a free exciton line, an edge emission due to recombenation of shallow donor-acceptor pairs and Mn2+-related intra-ionnic emissions. Te near band edge transition energies are determined lines in the PL spectra correspond quite well to the energies of the fundamental trasitions determinde from CER and SPS data. The parameters that descrbe the temperature dependence of the trasition energy of the fundamental band-edge excton are evaluated and discussed.

Effect of annealing on the physical properties of thermally evaporated In2S3 thin films

S. Rasool,K. Saritha,K.T. Ramakrishna Reddy,M.S. Tivanov,A.V. Trofimova,S.E. Tikoto,L. Bychto,A. Patryn,M. Maliński,V.F. Gremenok 한국물리학회 2019 Current Applied Physics Vol.19 No.2

The structural, compositional, morphological and optical properties of In2S3 thin films, prepared by thermal evaporation technique and annealed in sulfur ambient at different temperatures have been investigated. The grazing incident X-ray diffraction patterns have indicated polycrystalline form and predominantly cubic structure of annealed In2S3 films. The scanning electron microscopy revealed textured surface with uniformly distributed grains and the grain size increased with increase of annealing temperature. The optical parameters of the films have been determined using conventional transmission and reflection spectra as well as from surface photovoltage measurements.