Antimonide based avalanche photodiodes

There is a lot of interest in developing low noise avalanche photodiodes (APDs) in the short wave infrared (1.5-3 microns) and mid-wave infrared (3-5 microns). State of the art APDs are are based on based on interband transitions in mercury cadmium telluride (MCT, HgCdTe) with large multiplication gains and low excess noise factors due to the favorable bandstructure that promotes single carrier impact ionization. However, their dark currents are high (3-5e-4A/cm2 at a gain of 10 at 125K) that requires cryogenic cooling. We have investigated the multiplication characteristics of three different multipliers on InP substrate (AlGaInAs (M1), AlGaAsSb (M2) and AlInAsSb (M3)). We have demonstrated decrease in the excess noise factors using ternary superlattices and extremely low excess noise factors (k~0.01) and low dark current density (~10 A/cm2) at 300K. We will discuss the research challenges associated with the design, growth, fabrication and radiometric characterization of these APDs