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UDC 621.378At 4.2 K, the photoluminescence spectra of Cu(In,Ga)Se 2 films irradiated by electrons with an energy of 5 MeV displayed the 0.93-and 0.79-eV bands that owe their origin to the radiative recombination of nonequilibrium charge carriers on radiation-induced defects. The position of the energy levels of the defects is determined and their nature is discussed.Introduction. Creation of high-efficiency solar elements based on Cu(In,Ga)Se 2 (CIGS) is a topical scientifictechnical problem of contemporary semiconductor photoenergetics [1,2]. The value of the efficiency currently achieved for the solar elements based on CIGS is about 19.2% [3]. Here, particular attention is being given to the creation of radiation-resistant semiconductor photoconverters capable of functioning reliably and for a long time under the conditions of exposure to penetrating radiation, in particular, in outer space [4,5]. The most common method of determining the criteria of radiation resistance of CIGS solar elements and films under the ground-based conditions is to study the degradation of their parameters and physical properties on exposure to high-energy protons and electrons [6,7].In the present work, we describe experiments carried out to establish the nature of radiation-induced defects on irradiation by high-energy electrons in CIGS films commonly used in serial manufacture of solar elements with an efficiency of about 12-14% [8]. For the first time, to determine the influence of electrons on CIGS compounds, a nondestructive method (luminescence) is used, which allows one to register the formation of energy levels in the energy gap and to perform the identification of the type of defects formed on the atomic level.Experimental. We investigated thin (,1 µm) CIGS films, with p-type conductivity, which were grown directly on glass substrates or on a thin layer of molybdenum preliminarily sputtered onto glass. The elemental composition of the films was determined using x-ray spectral analysis and scanning Auger-electron spectroscopy. Exposure to electrons with an energy of 5 MeV was performed on a linear accelerator by a dose of about 10 18 cm -2 at a temperature less than 50 o C. The electron flux density was about 2⋅10 12 cm -2 ⋅sec -1 . The absorption spectra in the 0.2-3.0-µm region were registered on a Cary-500 UV-VIS-NIR two-beam spectrometer (Varian, USA), the photoluminescence spectra were obtained with the aid of an MDP-23U grating monochromator with the focal length of a mirror objective

The effect of a strong magnetic field (induction up to 10 T) on free and bound excitons in CuInS 2 single crystals is studied. A diamagnetic shift to higher energies is observed in the luminescence and reflectance spectra for free-exciton lines A LPB ≈ 1.5348 eV, A UPB ≈ 1.5361 eV, and BC ≈ 1.557 eV. The diamagnetic shifts of free-exciton lines A LPB , A UPB , and BC provide a basis for estimating the exciton reduced masses µ A LPB = 0.131m 0 , µ A UPB = 0.134m 0 , and µ BC = 0.111m 0 , respectively. Bound-exciton lines in luminescence spectra are split under the influence of the magnetic field. The magnitude of the Zeeman effect (g-factor of the magnetic splitting) is estimated.Introduction. The chalcopyrite semiconductor CuInS 2 has unique physical properties such as a high self-absorption coefficient α ≈ 10 5 cm -1 and a band gap E g ≈ 1.53 eV, which is a very good approximation to the maximum in the solar radiation spectrum [1]. This makes it very attractive to use CuInS 2 for fabrication of cheap and efficient solar cells [2][3][4]. However, only a limited number of publications on the study of the physical properties of structurally perfect CuInS 2 single crystals using classical optical methods, in particular, luminescence [1, 5-11] and reflectance [5,11], have appeared. More thorough studies of the nature of free and bound excitons, the exact value of the band gap, and the energy levels of intrinsic structure defects formed during growth of crystals or films are necessary to control the structural perfection, doping level, and recombination processes in this material (films, single crystals).It is well known that magneto-optical measurements are one of the reliable methods for studying exciton states and determining the nature of residual impurities and intrinsic structure defects in various semiconducting materials [12]. In our opinion, such information is critical for further improvement of the technology for fabricating highly efficient solar cells based on CuInS 2 chalcopyrites. Magneto-optical research was recently carried out only for CuGaS 2 [13,14] and CuInSe 2 [15] chalcopyrites. Similar research for CuInS 2 has not been reported because of the lack of high-quality single crystals, the optical spectra of which would exhibit rather narrow lines for free and bound excitons for observing magneto-optical effects.Herein the magneto-optical effect on free and bound excitons in structurally perfect CuInS 2 single crystals is studied for the first time using optical reflectance and photoluminescence (PL) under the influence of strong magnetic fields (up to 10 T) at 4.2 K.Experimental. High-quality CuInS 2 single crystals were grown by directed crystallization using a temperature gradient. The chemical composition of the elements in the crystals was determined by local x-ray spectral analysis on a Stereoscan 360 scanning electron microscope (Cambridge Instruments, UK) with an in-built AN100000 energy spectrometer (Link Analytical, UK) and by scanning Auger-electron spectroscopy on a PHI-660 spectrometer (...

UDC 621.378We have used low-temperature (4.2-78 K) photoluminescence to study defect formation processes in Cu(In,Ga)Se 2 films when bombarded by protons with energy 380 keV. We have observed formation of luminescence centers with deep levels at ,410 meV and 470 meV.