EXCIMER-LASER ETCHING OF GAAS, ALXGA1-XAS AND CUINSE2 IN CHLORINE ATMOSPHERE

We have studied laser-induced etching (LIE) of GaAs and AlxGa1-xAs (x = 0.2, 0.66, 0.8) under chlorine atmosphere. In addition, LIE, applied to CuInSe2 for the first time, was investigated with respect to surfa ce damage production and surface roughness at various laser energy den sities. It was found that the etch rates of AlxGa1-xAs are higher than that of GaAs at the same fluence increasing almost linearly with lase r fluence. However, the etch threshold for of AlxGa1-xAs (55 mJ/cm(2)) is lower than of GaAs (85 mJ/cm(2)). It could be observed that the ba ckground pressure of H2O and O-2 have no influence on the etch thresho ld of GaAs and AlxGa1-xAs during LIE with Cl-2 as reactive gas. Etchin g of CuInSe2 shows a complex etch rate dependence suggesting a combina tion of chemical and physical processes at the surface. Raman scatteri ng was used to show that the surface stoichiometry of CuInSe2 can be v aried from In-rich to Cu-rich by changing different laser parameters. However, in all cases there is crystal damage near the surface of the substrate. (C) 1998 Elsevier Science B.V.