Effect of deep levels induced by electron irradiation upon the charge transport mechanism and the pressure-dependent electrical properties of forward-biased p+- n- n+ GaAs diodes

Abstract

Results are presented on the effect of electron bombardment upon the charge transport mechanism and the pressure-dependent electrical properties of p +- n- n + GaAs diodes. It is shown that at low bias voltage the electron irradiation does not change the charge-carrier transport mechanism. A change of IVC of GaAs diodes induced by increase of the irradiation dose is due to a rise of resistance of the diode base, resulting from a compensation of the base after the bombardment and to the appearance of double injection of the charge carriers into the diode base. It is found that a sublinear section of the IVC, which appears at high irradiation dose, is a result of the formation of a near-anode stationary high-field domain. Analytical expressions are obtained which describe well the experimental IVC for the irradiated diodes. The sensitivity of the irradiated diodes to the hydrostatic pressure is described by means of analytical formulae and numerical calculations, taking into account the pressure dependence of the width of the gap, energies of the gap levels induced by irradiation, and the lifetime of the charge carriers injected into the base region. A rise of the sensitivity of the diodes to the hydrostatic pressure with the irradiation dose is due to the appearance of the radiation-induced states within the gap, which are weakly coupled to the extremum Γ l c.