ELECTRICAL MEASUREMENTS OF THE ELECTRON-IRRADIATION INDUCED E-TRAPS AND H-TRAPS IN GAAS UNDER HYDROSTATIC-PRESSURE

The change of resistivity of the 2. 3 Mev-electron-irradiated bulk n- and p-GaAs has been measured at hydrostatic pressure up to 5 kbar at RT. Corrections for the changes in free electron and hole mobilities with pressure have been neglected. The resistivity changes are explained by a dependence on the pressure of the ionization energy of the radiation-induced E- and H-traps. The results indicate that most of these radiation-induced levels move away from the conduction-band edge ( GAMMA //c-point) at a rate approximately 0. 8-1. 0) gamma //G, where gamma //G equals 11. 6 multiplied by 10** minus **6 ev bar** minus **1 is the energy gap pressure coefficient for GaAs at RT. The high changes in ionization energies of E2 to E5-traps by pressure are compared with the lower changes in ionization energies found for the deep-lying impurity levels. In accordance with the theoretical investigation, it was suggested that most of the investigated radiation-induced levels in GaAs are t//2-states of Ga- and As-vacancies.