Electrical and optical deep-level transient spectroscopic methods were used to investigate deep traps that originated from impurities in GaAs/W Schottky diodes. Two distinct electron traps (E1 and E2, with activation energies of 0.65 and 0.58eV, respectively) were detected by means of the electrical deep-level transient spectroscopy of samples which had been annealed at 650C. The variation in activation energy and trap density, with changes in Schottky barrier height, indicated that the E1 trap could be identified with the EL2 defect which was usually observed in GaAs that had been grown by metalorganic chemical vapor deposition. Also, the E2 trap was found to be due to impurities that diffused from the W film, and into the GaAs layer, during annealing. Four hole traps, with activation energies of 0.76, 0.55, 0.43 and 0.30eV, were detected by means of the optical deep-level transient spectroscopy of samples which had been annealed at 650C. A comparison of the activation energy for each hole trap, with previously reported data, indicated that the first 3 traps were due to Cr, Fe and Cu. The fourth trap was attributed to a native defect.

Y.Takanashi: Journal of Applied Physics, 1996, 80[8], 4389-94