Photosensitivity of thin-film structures based on CuIn<Subscript>3</Subscript>Se<Subscript>5</Subscript> and CuIn<Subscript>5</Subscript>Se<Subscript>8</Subscript> ternary semiconductor compounds

Polycrystalline n-type CuIn₃Se₅ and CuIn₅Se₈ films with thicknesses from 0.4 to 1 μm have been grown by pulsed laser ablation of bulk p-CuIn₃Se₅ and n-CuIn₅Se₈ crystals in vacuum. The temperature dependences of the resistivities of these crystals are determined by deep donor levels with energies E _D ? 0.2–0.3 eV. Photosensitive thin-film structures based on these films have been created for the first time and their photosensitivity spectra have been measured. The possibility of using thin CuIn₃Se₅ and CuIn₅Se₈ films in broadband photoconverters is demonstrated.     

Comprehensive study of the conditions for obtaining hydrogenated amorphous erbium- and oxygen-doped silicon suboxide films, <Emphasis Type="Italic">a</Emphasis>-SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>:H 〈Er,O〉, by dc-magnetron deposition

The results of a comprehensive study of the conditions for growing a-SiO _x :H 〈Er,O〉 films are presented. The effect of the composition of various erbium-containing targets (a-SiO _x :H <Er,O>, ErO _x , Er₂SiO₅, Er₂O₃, and Er), substrate temperature, and annealing temperatures in argon, air, and under conditions of SiH₄ + Ar + O₂ plasma glow is studied. In order to obtain a-SiO _x :H 〈Er,O〉 films with the highest photoluminescence intensity of erbium ions, it is recommended for the following technological conditions to be used: the substrate holder should be insulated from dc-magnetron electrodes and the working gas mixture should include silane, argon, and oxygen. Single-crystal silicon and metal erbium should be used as targets. The erbium target should be placed only in the Si-target erosion zone.     

Experimental determination of the spatial distribution of electron defects in La2 ? xSrxCuO4 and Nd2 ? xCexCuO4 crystal lattices

The data of M?ssbauer emission spectroscopy on ⁶⁷Cu(⁶⁷Zn) and ⁶⁷Ga(⁶⁷Zn) isotopes show that holes appearing as a result of the Sr²⁺ substitution for La³⁺ in the La_{2 − x} Sr _x CuO₄ crystal lattice are localized predominantly at oxygen atoms occurring in the same atomic plane as the copper atoms. In contrast, electrons appearing as a result of the Ce⁴⁺ substitution for Nd³⁺ in the Nd_{2 − x} Ce _x CuO₄ crystal lattice are localized in the copper sublattice. These results are consistent with the model assuming that a mechanism responsible for the high-temperature superconductivity in La_{2 − x} Sr _x CuO₄ and Nd_{2 − x} Ce _x CuO₄ crystal lattices is based on the interaction of electrons with two-site two-electron centers possessing negative correlation energies (negative-U centers).     

Evaluation of the conversion efficiency of thin-film single-junction (a-Si:H) and tandem (μc-Si:H + a-Si:H) solar cells by analysis of the experimental dark and load current-voltage (I–V) characteristics

The aim of the study is to apply a method commonly used to determine the efficiency of multi-junction nanoheterostructure III?CV solar cells by analysis of the dark current-voltage (I?CV) characteristics to such an unconventional semiconducting material as amorphous silicon. a-Si:H and a-Si:H/??c-Si:H p-i-n structures without a light-scattering sublayer or an antireflection coating are studied. The results of measurements of the dark I?CV characteristics demonstrate that the voltage dependence of the current has several exponential portions. The conversion efficiency of solar cells (SCs) is calculated for each portion of the dark I?CV characteristic. This yields a dependence of the potential SC efficiency on the generation current density or on the photon flux. The observed agreement between the data derived from the experimental characteristics and results of calculations can be considered satisfactory and acceptable, thus the method suggested for measurement and analysis of dark I?CV characteristics and tested earlier on SCs based on crystalline III?CV compounds acquires a universal nature. The analysis of the characteristics of p-i-n amorphous silicon structures and the calculation of potential efficiencies, based on this analysis, extend the authors?? understanding of this class of devices and make it possible to improve the technology and photoconversion efficiency of SCs of this kind.