Defects in MOVPE grown ZnSe on GaAs studied by deep level transient spectroscopy

Abstract

Abstract The defect related properties of MOVPE grown ZnSe layers on GaAs were investigated by electrical measurements. Ditertiarybutylselenide and dimethylzinc-triethylamine were used as precursors for the ZnSe growth. In order to carry out nitrogen doping trimethylsilylacide triallylamine and bisditrimethylsilylamido-zinc were used as N precursors. The N doping was also performed by N 2 dc-plasma. Current-voltage ( I - V ) and capacitance-voltage ( C - V ) measurements reveal n-type behavior in all cases. The N D − N A net doping concentration amounts to 10 16 –10 17 cm −3 . An electron trap center with a thermal activation energy in a range of 0.30 to 0.33 eV and a capture cross section of about 10 −15 cm 2 was determined by means of deep level transient spectroscopy and isothermal capacitance transient spectroscopy measurements. This trap was detectable in all N-doped samples except in the case of a TMSiN doped sample. Since an electron trap center with comparable features has been also found in n-type single crystalline ZnSe and, as reported by other groups, also in n-type MBE ZnSe, it is assumed, that the existence of this state is related to a native defect in the as grown layer.