Photoluminescence of Bi2O3-InSe heterojunctions [Articol]

Abstract

Optical and photoelectrical properties from the immediate proximity of the band gap in the strongly anisotropic crystals constitute a major technical interest. The stratified structure specific of AIIIBVI group crystals determine the anisotropy of their physical properties [1-3]. Among intensely researched crystals from this group , there are the GaSe and InSe compounds [4-7]. The optical band of InSe crystals has a width of 1. 238 at T = 293 K [8]; this material is attributed to the group of promising semiconductors for photodetectors and elements of solar energetic [9-11]. At the same time, the low concentration of surface states points out the opportunity of using this material in the form of a thin layer, both GaS and GaSe, as an element of supernetworks and structures with quantum points being photoconducting and photoluminescent in the near IR spectra [12]. Studies concerning stability of characteristics of the InSe crystals and the photovoltaic structures based on them, under the effect of ionizing radiation and particles with high energy (protons, neutrons) have proven that, as a result, photosensibility increases [13, 14]. Photoelectric and photoluminescent proprieties depend on the diagram of the states localized in the gap band of the materials and on their recombination properties. Numerous data on the spectra of recombination levels induced by the structural defects and the atoms of impurities in the InSe crystal, purposefully doped or nondoped, can be obtained from the analysis of the optical spectra and photoluminescence [15-19]. The thermal treatment of monocrystals leads to Se atoms emission and to occupancy of intrinsic vacancies by impurity atoms. The vacancies from the InSe monocrystals surface layer are actively occupied by oxygen atoms, and the InSe-In2O3 semiconductor junction formation, photosensible in large spectra of wavelengths [20-22]. The aim of this work consists in the characterization of the process of recombination of nonequilibrium charge carriers, through radioactive states created at the interface of InSe-Bi2O3 heterojunctions.