Electron and neutron radiation-induced order effect in gallium arsenide

Electron (7 MeV) and neutron (1 MeV equivalent fluence damage in silicon) radiation effects in GaAs grown by the metallorganic chemical vapor deposition method are investigated. One series of samples was intentionally undoped, and another was doped n-type to 2.5×10¹⁵ Si/cm³. The fluences ranged from 10 ¹⁰ to 6×10¹⁵ cm^-2 for electron irradiation and from 10¹² to 3×10¹⁵ cm^-2 for fission spectrum neutron irradiation expressed as 1 MeV equivalent fluence in silicon. The radiation damage was characterized by low-temperature photoluminescence (PL) measurements using 1.58 eV laser excitation, deep level transient spectroscopy and transport measurements. The observed decrease of trap concentration accompanied with an increase in PL intensity at lower fluences, an increase in the density of traps at higher fluences, and a fluence-dependent oscillatory PL intensity for acceptor levels indicate radiation-induced order at low fluences following by nonuniform reorganization of defects with radiation in GaAs