Electron irradiation-induced increase of minority carrier diffusion length, mobility, and lifetime in Mg-doped AlN∕AlGaN short period superlattice

Abstract

Minority carrier diffusion length in a p-type Mg-doped AlN∕Al0.08Ga0.92N short period superlattice was shown to undergo a multifold and persistent (for at least 1week) increase under continuous irradiation by low-energy beam of a scanning electron microscope. Since neither the diffusion length itself nor the rate of its increase exhibited any measurable temperature dependence, it is concluded that this phenomenon is attributable to the increase in mobility of minority electrons in the two-dimensional electron gas, which in turn is limited by defect scattering. Cathodoluminescence spectroscopy revealed ∼40% growth of carrier lifetime under irradiation with an activation energy of 240meV.