Photocapacitance characterization of deep levels in InGaAs/GaAsSb type-II MQW photodiodes

Promising results of InGaAs/GaAsSb material systems suggest that it is an alternate for extended InGaAs and HgCdTe in the SWIR region. Understanding the dark current that is caused by the deep level will further improve device performance. In this work, photocapacitance under constant capacitance method was used to characterize the deep levels in the InGaAs/GaAsSb type-II quantum well photodiode for the first time. Deep levels are identified at 0.28 eV, 0.32-0.34 eV, 0.47 eV, and 0.65 eV from the photocapacitance results. Deep levels at 0.28 eV, 0.47 and 0.65 eV are from the InGaAs layers, possibly donor like defect. Deep levels at 0.32-0.34 eV are from the GaAsSb layer contribution, possibly acceptor like defect. Estimated deep level density of the type-II InGaAs/GaAsSb MQW sample is around 1 × 1014 cm−3.