Electron barrier study of mid-wave infrared interband cascade photodetectors

In this paper, we report our experimental investigation on the influence of electron barrier (eB) in mid-infrared interband cascade photodetectors. Even though earlier theoretical projection indicates that an eB with 2-pairs GaSb/AlSb quantum wells (QWs) is sufficient to block electrons direct tunneling between stages, our experimental results show that a thicker (with 6-pairs of GaSb/AlSb QWs) electron barrier could significantly reduce the device dark current, with little influence on the optical performance. The 5-stage devices have demonstrated a dark current density of 1.10 × 10−7 A/cm2 (at −5 mV) and a Johnson-limited D* of 1.81 × 1011 cmHz1/2/W (at 3.8 μm) at 150 K, respectively.