The development of extremely low noise InAs electron APDs for photon counting applications in SWIR/MWIR wavelengths

In this work we report on InAs avalanche photodiodes (APDs) that exhibit high gain with extremely low excess avalanche noise. Our measurements showed that InAs has significantly larger electron ionization coefficient than most compound III-V semiconductors and extremely small hole ionization coefficient. This large electron to hole ionization coefficient ratio leads to excess noise factor, F~2 when electrons initiated the multiplication process in our APDs. Significantly larger excess noise factors were measured when both electrons and holes were injected into the avalanche region to initiate the multiplication process. Our InAs APDs demonstrated ionization characteristics similar to those observed in Cadmium Mercury Telluride (CMT) in the short wave infrared (SWIR). Measurements of temperature dependence of leakage current provided early indications of potentially higher operating temperature than CMT. The low excess noise behaviour and higher operating temperatures, demonstrate that InAs APDs have potential to be developed into low cost high performance photon counting APD arrays to rival CMT.