Copper as an electron trap in GaAs0.6P0.4

An electron trap having an energy level of 0.14 eV from the conduction band edge was found in the bulk of copper-diffused VPE-grown n-GaAs_0.6P_0.4 by conventional DLTS measurements and by pulse-duration dependent capacitance amplitude measurements. The capture cross section at room temperature is about 1.0×10^–21 cm² and has a weak temperature dependence. These properties are attributed to a non-repulsive center having a capturing mechanism which involves multiphonon emission processes with hardly any lattice relaxation. Evolution of the spatial distributions of the traps with time under junction electric field were studied. The results suggest that the trap is positively charged and has a high diffusivity under electric field. The center can thus be identified as positively charged interstitial copper ion rather than some form of copper complexes.