High-performance room temperature 2.75  µm cutoff In_0.22Ga_0.78As_0.19Sb_0.81/Al_0.9Ga_0.1As_0.08Sb_0.92 avalanche photodiode

Extended shortwave infrared (eSWIR) detectors capable of detecting wavelengths between 1.7 and 2.7 µm are useful for a wide range of applications, such as remote sensing and monitoring, but most of these detectors require cooling to reduce the dark currents. Identifying a suitable material that extends the wavelength range to well beyond 2 µm with minimal cooling is therefore important. The overall sensitivity of such a detector can be enhanced by using it in conjunction with a wide bandgap multiplication region which can increase the photocurrent via impact ionization. In this work, a systematic study of avalanche multiplication in seven Al 0.9 Ga 0.1 As 0.08 Sb 0.92 diodes lattice matched to GaSb shows that the electron impact ionization coefficient ( α ) is larger than the hole impact ionization coefficient ( β ), especially at low electric fields. Using In 0.22 Ga 0.78 As 0.19 Sb 0.89 (bandgap=0.45eV) as the absorber and Al 0.9 Ga 0.1 As 0.08 Sb 0.92 (bandgap=1.6eV) as the multiplier in a separate absorption, charge, and multiplication region avalanche photodiode configuration enabled room temperature optical detection up to 2.75 µm with a peak external quantum efficiency (EQE) of >50% at the punch-through voltage ( V pt ) ∼2µm wavelength. This device demonstrates a low excess noise of F =4.5 at a multiplication of M =20, giving rise to a noise equivalent power for an unoptimized device of 1.69×10 −12 W/Hz. A maximum multiplied EQE of >2000% at 2 µm is achieved before a low breakdown voltage of 18.9 V, obtained using a novel undepleted absorber design. This work shows the possibility of a high sensitivity eSWIR detector capable of operating at room temperature.