Development of AIIBVI Semiconductors Doped with Cr for IR Laser Application

Abstract

Electrical and optical measurements obtained with CdSe single crystals doped with chromium from a gas source CrSe over a wide temperature range (500-1050 °C) are compared with ZnSe annealed in liquid metal (Zn). These processes are intended to control the concentrations of the impurity and intrinsic defects. The low temperature annealing of CdSe crystals in CrSe atmosphere allows obtaining high electron mobility up to 9000 cm 2 /Vs at 80 K and demonstrates the low native defect concentration. A high temperature annealing gives rise to increased electron concentration with decreased mobility. Optical absorption measurements show that at the high annealing temperature effective doping with Cr takes place. The impurity absorption beyond the absorption edge is interpreted by the excitation of Cr ÷+ and Cr+ deep levels.

Optical and transport properties of chromium-doped CdSe and CdS0.67Se0.33 crystals

“…This method allows growing of large (more than 50 mm in diameter) untwinned single crystals of II-VI semiconductors [8,9]. Doping by post-growth in-diffusion is popular for lasing materials preparation, and it has been used for Cr-doping of ZnSe and CdSe crystals [10,11]. However, indiffusion can induce defects resulting from loss of stoichiometry caused by the large difference in vapor pressures of the constituent elements [12].…”

“…8 shows the temperature dependence of the Hall mobility, m H , calculated from the experimental values of the conductivity, s, and the Hall coefficient (m H ¼ R H Â s). For the CdSe:Cr samples the mobility increases as the temperature decreases down to 50 K. For these samples the Hall mobility reaches a value 6000 cm 2 /Vs at 50 K, and the maximum value of m H practically does not depend on the chromium concentration and is close to m H for undoped CdSe single crystals [11]. It the temperature range from 100 to 300 K, the temperature dependence of the Hall mobility in CdSe:Cr obeys the T À1.5 law, which is typical for lattice scattering of charge carriers.…”

En route to electrically pumped broadly tunable middle infrared lasers based on transition metal doped II–VI semiconductors

“…The n-type samples were obtained by subsequent diffusion of Al impurities [50,51]. The crystals were placed on top of mixture of Zn and Al powders (97 wt% of Zn and 3 wt% of Al), and again placed in identical evacuated ampoules.…”

EPR Spectra of Cr in CdTe Crystals

“…Cr-based diluted magnetic semiconductors are also promising materials for new optoelectronic devices e.g. tunable mid-infrared lasers (CdSe:Cr, ZnSe:Cr, CdMnTe:Cr [4]), converters of red-green into blue light [5]. The observed ferromagnetic p−d exchange interactions in zinc chalcogenides recommends them as the material for spintronics as well [2,6,7].…”