Optimizing broadband InGaAs/InP photodetectors for the SWIR range

Two aspects of pin infrared photodetectors with InGaAs as the active layer for the short-wave infrared range (900 to 1700 nm) were optimized. The first one involved using a novel anti-reflective coating formed by two double layers of SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, which presented an average 30% reduction in total reflectance compared to a device without the anti-reflective coating. The second one consisted of introducing a quaternary InGaAsP layer between the active InGaAs layer and the n-doped InP layer to reduce interface losses. An extraordinary increase by a factor of six in the responsivity of the device with the quaternary layer was reached.