Influence of electron irradiation on p–n junctions in Si–Ge superlattices

Abstract

The influence of 3–4 MeV electron irradiation on the electrical properties of p–n junctions formed inside Si_6Ge_4 superlattices (SLs) has been studied. The current–voltage characteristics and capacitance–voltage (C–V) profiles have been measured in the temperature range from 4.2 to 300 K. Negative differential conductance (S-type current–voltage characteristics) was observed at 77 K after irradiation. The carrier removal rate upon electron irradiation of the Si–Ge SL does not differ from that of a SiGe alloy with a comparable doping level, which is at variance with the formerly obtained data on a higher radiation hardness of the photoluminescence in similar SLs. We conclude that the radiation hardness is parameter-specific: making a characteristic of a quantum-size semiconductor structure more radiation tolerant does not mean the same improvement with respect to other parameters.