Some Failure Mechanisms in Charge-Sensitive Infrared Phototransistors

For an infrared photon detector, such as charge-sensitive infrared phototransistors (CSIPs), we propose and use a capacitive charging method to study some failure mechanisms that disable the photon response of CSIPs. Two failure mechanisms are highlighted, namely interquantum well (QW) leakage and low tunneling probability for intersubband-transition-excited electrons. A correlation between the Al content in the inter-QW AlGaAs barrier and the failure mechanism type are discussed. On the other hand, the previously unexplained puzzle that the success of photon response is only weakly dependent on the QW electron mobility that is attributed to an imperfect inter-QW barrier.