HIGHLY COMPENSATED GAAS CRYSTAL OBTAINED BY MOLECULAR CO-DOPING

GaAs:C crystal was grown by liquid encapsulated Czochralski technique with large partial pressure of CO in ambient atmosphere p(CO)/p(tot) = 0.2 and investigated using near and infrared absorption, photolumines cence, photoconductivity, photo-induced current transient spectroscopy and photo-Hall measurements. High resistivity of the crystal was foun d in electrical measurements (10(7) OMEGA cm, the Fermilevel at 0.67 e V below conduction band at 300 K). Local vibrational mode revealed inc reased concentration of carbon acceptor and presence of oxygen related complexes. Photoluminescence spectra were dominated by two bands with peak energies at 1.49 eV and 0.8 eV. The near band gap emission shift s with excitation intensity up to 4 meV/decade. In photocurrent spectr um a strong photoionization band with E = 0.55 eV is observed.