EFFECT OF PULSED-LASER IRRADIATION ON THE OPTICAL CHARACTERISTICS ANDPHOTOCONDUCTIVITY OF THE SOLID-SOLUTIONS CDHGTE

The melting threshold of Cd0.2Hg0.8Te has been determined by numerical modeling of the irradiation of the material with nanosecond ruby-lase r radiation pulses: W-n=40-50 mJ/cm(2) with initial crystal temperatur e T-0 = 100 K and W-m = 30-40 mJ/cm(2) at T-0 = 300 K. Laser-induced m odification of the surface of the sample under irradiation with energy density W< W-m was found; it was manifested as a quenching of the sta tionary photoconductivity and an increase in the reflection coefficien t. For laser irradiation with W above the melting threshold, the refle ction coefficient increases further in the region up to W greater than or similar to 100 mJ/cm(2) and decreases for W>110 mJ/cm(2). For abov e-threshold irradiation, the photoconductivity signal was found to dec rease monotonically with increasing energy density in the laser pulse; this can be explained by defect formation caused by laser-induced var iation of the composition in the surface region. (C) 1997 American Ins titute of Physics.