Long-Time Relaxation and Residual Conductivity in GaP Irradiated by High-Energy Electrons

Abstract

This paper presents the results of a study of long-time relaxation (LR) and residual conductivity in n-type gallium phosphide (GaP) crystals irradiated by 50 MeV electrons. A manifold increase in photosensitivity and quenching of residual conductivity was found as a result of irradiation. It is shown that LR in GaP is due to disordered regions (generated by electron irradiation) which have conductivity close to self one. The Fermi level in the disordered regions is determined by which is located deep in the forbidden band (Е е − 1.0 eV). LR effect is mainly explained by a spatial separation of electrons and holes, recombination of which is prevented by potential barriers. The observed increase in conductivity is associated with the increase in the concentration of minority carriers as well as with increase of the Hall mobility at the sample illumination.

Scattering of Conduction Electrons on the Static Deformation Raised by Irradiation in n-GaP Crystals

“…Here, α/n ratio after irradiation increases. When irradiating with 50 MeV electrons, point radiation defects and more thermo-stable disordered regions are simultaneously formed in GaP crystals [8] [9]. Figure 2 shows the absorption spectra of the crystals: the non-irradiated, irradiated (50 MeV electrons at a dose of 10 17 el/cm 2 ) and after heat treatment at 525˚C.…”

“…In this connection it is interesting to note a much greater influence on the basic absorption edge in GaP, exerted by radiation defects in comparison with impurity centers, which is also explained by deformation effects [8] [9].…”