EFFECTS OF IMPACT IONIZATION ON IV CHARACTERISTICS OF GAAS N-I-N STRUCTURES INCLUDING HOLE TRAP

Numerical simulations of GaAs n-i-n structures with Cr deep acceptors (hole trap) in the i-layer are performed by considering the impact ionization of carriers. At low voltages, I-V curves show sublinear or saturated features, because the voltage is entirely applied along the reverse-biased n-i junction. When the deep-acceptor density is low, a steep rise of current occurs due to trap filling, while when the deep-acceptor density becomes high, the steep current rise occurs due to impact ionization of carriers at the reverse-biased n-i junction. In this case, the voltage for current rise becomes lower as the acceptor density becomes higher.