PREFERENTIAL (111) ORIENTATION OF ZNSE ON (100) GAAS DEPOSITED BY LASER-INDUCED MOCVD

Thin films of ZnSe have been deposited on (100) GaAs substrates from dimethylzinc (DMZn) and diethylselenide (DESe) using direct ArF excimer laser irradiation of the growth surface. Films deposited by this method are of inferior crystalline quality compared with equivalent MOCVD-grown material, exhibiting (400) FWHM values of ∼ 5° at standard MOCVD epitaxial deposition temperatures. This was attributed to excessive carbon levels in the layer due to the incorporation of alkyl group photolysis byproducts. The deposited ZnSe also shows a marked tendency to preferential (111) orientation which increases with increasing irradiance. The (111)-oriented material also exhibits superior crystallinity to (100)-oriented material grown deposited under equivalent conditions and this is attributed to an increased rejection of carbon bearing species under 193 nm irradiation. A mechanism involving the anisotropic creation of energetic photocarriers which stimulate surface reactions is proposed. © 1990.