Effects of traps on the dark current transients in GaAs/AlGaAs quantum-well infrared photodetectors

Abstract

In this work, experimental results showing very slow (up to 10 4 s) dark current transients in n-type GaAs/Al 0.27Ga 0.73As quantum-well photodetectors (QWIPs) are reported. The transients with amplitudes of 0.1% to 65% of the steady-state current have been observed at 77 K. These effects are believed to be associated with initially ionized deep levels acting as traps reducing the positive charge in the structure. The time constant of the dark current (transient) decreases with increasing temperature with an experimentally determined activation energy ∼75 meV . A fitting of the capture cross section to σ(T)=σ 0 exp(E c /k B T) gives an estimate for the capture activation energy of E c∼35 meV.