Improved planar InAs avalanche photodiodes with reduced dark current and increased responsivity
Indium Arsenide (InAs) infrared photodiodes provide high quantum efficiency in the wavelength range of 1.0 to 3.0 µm. Planar diode configuration has been adopted to reduce surface leakage. In this work, new fabrication procedures for planar InAs avalanche photodiodes (APDs) are reported. Beryllium (Be) ions were implanted into InAs at a relatively low energy of 34 keV. Effects of duration of post implant annealing on the electrical characteristics of InAs APDs were investigated. It was found that a combination of post implant annealing at 500 °C for 15 minutes and a shallow surface etch produces planar APDs with good characteristics (room temperature dark current density of 0.52 A/cm2 at -0.2 V and external quantum efficiency of 51% at 1520 nm at ‑0.3 V). These represent a 3 times reduction in dark current and 1.4 times increase in responsivity, compared to earlier Be‑implanted planar InAs APDs. The APDs’ avalanche gain characteristics remain similar to those from earlier reports, with a gain of 4 at a relatively low operating bias of 5 V. This suggests the potential of integrating InAs APDs with low voltage readout integrated circuits (ROIC) for development of infrared imaging arrays. The data reported in this paper is available from the ORDA digital repository (DOI: 10.15131/shef.data.6955037).