EFFECTS OF DEEP LEVELS AND SI-DOPING ON GAINP MATERIAL PROPERTIES INVESTIGATED BY MEANS OF OPTICAL METHODS

Deep level characteristics in undoped and Si-doped Ga0.51In0.49P layer s has been investigated using photocapacitance and photoluminescence ( PL) methods. Ga0.51In0.49P layers were grown by metalorganic vapor-pha se epitaxy in the temperature range 600-730 degrees C and with doping levels from 3.9 x 10(17) cm(-3) to 1 x 10(19) cm(-3). A dominant deep level with an activation energy of about 0.98 eV was observed in all u ndoped samples. Further deep levels have been found with activation en ergies in the range 0.43-0.50 eV. Undoped samples grown at 650 degrees C exhibit the lowest trap concentration, with one remaining level at 0.89 eV only. A direct link of PL intensity to non-radiative recombina tion due to deep centers is demonstrated. Undoped samples exhibit the highest PL intensity at the growth temperature of lowest deep level de nsity. Si doping suppresses the main deep level at Delta E(T) = 0.89 e V and results in an increase of PL intensity up to N-D = 2 x 10(18) cm (-3). Only deep levels in the energy range 0.41-0.50 eV were detectabl e. No DX-like effects due to Si doping were observed.