Laser annealing of defects in CdTe epitaxial layers

Abstract

Hall-effect, photoluminescence and DLTS measurements have been used to investigate defects in laser-annealed CdTe epilayers. The In-doped CdTe films were growb by hot-wall epitaxy on BaF2 substrates. Laser annealing was performed using the radiation of a high-power cw Kr+ laser. Above a certain threshold power photo-induced sublimation occurs; the corresponding temperature is far below the melting temperature. Laser annealing with subthreshold powers increases both the electron concentration and the mobility. Mobility values around 300 cm2/V · s at room temperature have been obtained. From photoluminescence measurements it has been concluded that the increase in the carrier concentration is caused by an activation of the In donors. DLTS measurements have shown that laser annealing is able to reduce the concentration of two defects by one order of magnitude without introducing a new defect as in the case of thermal annealing. © 1985.