Mapping of GaAs wafers by IR light diffraction and luminescence

Abstract Optical investigations were carried out on undoped as well as on Cr-doped semi-insulating GaAs(100) wafers. The distribution of the non-equilibrium charge carrier grating erasure time τ E across GaAs wafers has been investigated by means of picosecond laser-induced dynamic grating and picosecond-photoconductivity techniques. Additional photoluminescence data have been obtained to reveal the contamination of GaAs wafers. The influence of high temperature annealing conditions on the distribution of the deep level EL2 and on the τ E mapping data has been studied. Also, feasibility of dynamic grating and picosecond-photoconductivity techniques for checking GaAs wafer quality is shown. Recombination through the deep levels EL2 and Cr are discussed.