Radiation-induced deep levels in n-type GaAs grown by metal-organic chemical-vapor deposition

We report a comprehensive study of deep levels in the entire band gap of alpha-irradiated n-type GaAs, grown by metal-organic vapor phase epitaxy (MOVPE), over a wide temperature scan range of 12-475 K. Deep level transient spectroscopy (DLTS) reveals the presence of, at least, seven radiation-induced deep level defects at energy positions E-c-0.05 eV, E-c-0.14 eV, E-c-0.19 eV, E-c-0.34 eV, E-c-0.38 eV, E-c-0.59 eV and E-c-0.69 eV in the upper-half of the band gap, while two radiation-induced defects at energy positions E-v+0.54 eV and E-v+0.77 eV were observed in the lower-half band gap. Some significant differences have been observed with respect to the published work on Schottky barrier diodes. Detailed data on the emission rates, capture cross-sections and introduction rates of the radiation-induced defects are presented. The majority carrier emitting levels at E-c-0.05 eV and E-c-0.14 eV have been found to have electric-field-dependent emission rate signatures. (C) 2009 Elsevier B.V. All rights reserved.