DEEP-LEVEL TRANSIENT SPECTROSCOPY CHARACTERIZATION OF ELECTRON-IRRADIATION-INDUCED HOLE TRAPS IN P-GAAS GROWN BY MOLECULAR-BEAM EPITAXY

Schottky barrier diodes on Be-doped p-type GaAs grown by molecular beam epitaxy (MBE) were irradiated with electrons (beta particles) from a Sr-90 radio-nuclide. Using deep level transient spectroscopy (DLTS), the radiation induced hole traps, labelled H beta 1 - H beta 7, were characterized. The three most prominent defects, H beta 1, H beta 4 and H beta 5, have energy levels at 0.08, 0.20 and 0.30 eV, respectively, above the valence band. The introduction rate of H beta 1 is close to those of the electron irradiation induced electron traps E1 and E2 in n-GaAs, which have been identified as two charge states of the isolated As vacancy, V(As). Defect H beta 4, whose concentration decreases with depth below the metal-GaAs interface, has not yet been reported for electron irradiated GaAs.