Temperature dependent characteristics of AlGaAsSb single photon avalanche diodes

Near-infrared Single Photon Avalanche Diodes (SPADs) are practical single photon detectors, particularly for applications requiring high operating temperatures. Compared to established InP SPADs, AlGaAsSb SPAD offers superior thermal stability but currently exhibit lower single photon detection efficiency. To improve their performance, origin(s) of AlGaAsSb SPAD's dark count rate (DCR) and detection efficiency versus overbias characteristics should be investigated. We explore these by performing extensive DCR and SPDE measurements on InGaAs/AlGaAsSb SPADs in gated mode at relevant temperatures (200 -290 K). The maximum SPDE at 1550 nm wavelength was 31 (4 V overbias) and 20 % (3 V overbias) at 200 and 250 K, respectively, higher than earlier reports of AlGaAsSb SPADs. DCR data analyses show that the tunneling current is a dominant DCR mechanism over the range studied. It most likely originated from the InGaAs absorber, despite an attempt to reduce the electric field in the design. It is therefore necessary to ensure the entire InGaAs absorber does not experience a relatively high electric field in future designs of AlGaAsSb SPADs. If AlGaAsSb SPADs without tunnelling current can be achieved, their single photon detection performance is expected to match that of InP SPADs at least, while exhibiting superior thermal stability.