DLTS Study for Energy-Broadening of the Defect Level on Introducing Radiation Damage in GaP

Measurements of deep-level transient spectroscopy (DLTS) have been made on the n-GaP before and after electron irradiation at 10 MeV. The density of an electron trap with an activation energy of 0.38 eV, which originally exists in the as-grown crystal, is reduced by the irradiation at an average reduction rate of 0.07 cm -1 . The DLTS spectrum for this trap is broadened with irradiation and sharpened with successive annealing. The level broadening Δ E t of the trap is estimated by the simulation technique. Δ E t increases (decreases) with increasing (decreasing) width of the DLTS spectrum according to the introduction (annihilation) of radiation defects. The calculated average potential fluctuation is close to Δ E t (=70 meV) for the irradiated sample with 1 × 10 17 electrons/cm 2 , implying that the level broadening arises from the band-edge broadening.