RESONANT RAMAN STUDIES OF SURFACE-COMPOSITION AND STRUCTURAL ORDERINGIN LASER-IRRADIATED HG1-XCDXTE

Resonant Raman scattering has been used to study the effects of high-p ower laser annealing on Hg1-xCdxTe for x = 0.165 and x = 0.18. The ann ealing was performed in air with a Nd:YAG laser tuned to the first har monic. A pulse duration of 72 ns and irradiation energy densities of 2 70 and 400 mJ/cm(2) were used. Information on both the structural orde ring and the alloy composition in irradiated Hg1-xCdxTe was obtained b y resonance Raman spectroscopy with laser photon energies of between 2 .41 and 2.54 eV. The presented Raman spectra from annealed samples ind icate structural disorder and a decrease in the degree of alloying as a result of Hg outdiffusion and segregation caused by laser-induced no nequilibrium melting and solidification. Moreover, a shift of the maxi mum resonant enhancement for the TO2, LO2, A, and LO1&TO1 modes in the case of a Hg0.82Cd0.18Te sample, annealed by 400 mJ/cm2 laser pulse, to higher photon energy points to an increase in the composition from x = 0.18 to x approximate to 0.3.