Recovery and accumulation of ion irradiation damage leading to dose rate dependence in GaAs

Abstract

Competing dynamics was analyzed for generation, recovery and accumulation of ion irradiation damage using three methods including He-ion channeling backscattering. The in situ tracing of electrical conductance after pulsed 100 keV proton irradiations at 23 °C–92 °C revealed that the subsequent recovery process was a second-order reaction with an activation energy of 0.74 eV in n-type and 0.31 eV in p-type epitaxial layers arising from long-range migration of both Ga and As interstitials. The amorphized depth by pulsed irradiations exhibited that the recovery was suppressed by the incidence of two ions within a lateral separation, which increased from ∼5 to ∼20 nm with the ion mass for 80 keV Ne+, 150 keV Ar+, and 300 keV Kr+ ions of an identical projected range, 115 nm. From the comparison with ion-collision simulations, it was concluded that if two collision cascades overlap before the recovery, it enhances interstitial clustering while suppressing the annihilation and causes the dose rate dependence.