Phys.org February 9, 2023
Avalanche photodiodes (APDs) have internal gain, which means that when compared to PIN-photodiodes they typically have a higher signal-to-noise ratio. Researchers in the UK designed and demonstrated photodiode that exhibits high multiplication factor with very little added noise. The new semiconductor alloy is based on a GaAsSb absorption region that has excellent detection efficiency at infrared wavelengths (up to 1,700 nanometers). The device incorporated an appropriate doping profile to suppress tunneling current from the absorption region, achieving a large avalanche gain, ∼130 at room temperature. It exhibits extremely low excess noise factors of 1.52 and 2.48 at the gain of 10 and 20, respectively. At the gain of 20, their measured excess noise factor of 2.48 is more than three times lower than that in the commercial InGaAs/InP SAM-APD. The result, with an excess noise factor of 2.48, is approaching the theoretical lower limit of 2. This provides the pathway to realize extremely low noise APD that the researchers believe can generate step changes in optical communication and long range LIDAR… read more. Open Access TECHNICAL ARTICLE
Room temperature dark current density of 200, 100, and 50 μm radius devices… Credit: Applied Physics Letters, Volume 122, Issue 5, 31 January 2023