Post-growth annealing of CdS crystals grown by physical vapor transport

摘要: Abstract In this study, the photoluminescent and electric properties of as-grown CdS crystals effects observed after post-growth annealing in a cadmium, sulphur, selenium overpressure were investigated. Bulk grown by physical vapor transport (PVT) from high-purity starting materials, two types crystals, one "dark" other "clear" obtained both having medium resistivity 106-108 l)-cm. The "dark"-type are cadmium rich, as evidenced an emission peak centered around 2.07 eV, which may be attributed to sulphur vacancies, while is less pronounced. Heat treatment under cadmium-vapor atmosphere has effect decreasing approximately 5 orders magnitude, at 500°C, increases 4 magnitude creates new 620 nm (2 eV). 1. Introduction Cadmium sulphide (CdS) important useful material for optoelectronic applications. growth been intensively studied many years [1-3]. A relatively high concentration defects resulting temperature required previous methods led low reproducibility results. Recently, modification PVT method was * Corresponding author. Fax: +1 615 329 8634; E-mail: aburger@dubois.fisk.edu. I Present address: Universities Space Research Association, Huntsville, Alabama, USA. reported [4] produces, lower temper- atures, large dislocation density second-phase inclusion density. Undoped always n-type, (PL) extensively past with respect its conversion type. Most PL context intentionally doped [5-7]. Other authors found [8-10] that heat illumination treatments affect general features their lumi- nescence spectra. CdS, good model investigation optical electronic pressure, became focus several studies [11,12], renewed interest triggered recent reports on development electron-beam- pumped devices [13,14]. 0022-0248/96/$15.00 Copyright © 1996 Elsevier Science B.V. All rights reserved