MAPPING OF GAAS WAFERS BY IR LIGHT-DIFFRACTION AND LUMINESCENCE

Optical investigations were carried out on undoped as well as on Cr-do ped semi-insulating GaAs(100) wafers. The distribution of the non-equi librium charge carrier grating erasure time tau(E) across GaAs wafers has been investigated by means of picosecond laser-induced dynamic gra ting and picosecond-photoconductivity techniques. Additional photolumi nescence data have been obtained to reveal the contamination of GaAs w afers. The influence of high temperature annealing conditions on the d istribution of the deep level EL2 and on the tau(E) mapping data has b een studied. Also, feasibility of dynamic grating and picosecond-photo conductivity techniques for checking GaAs wafer quality is shown. Reco mbination through the deep levels EL2 and Cr are discussed.