Characteristics of InAlGaAs/InAlAs Superlattice Avalanche Photodiodes for Ultra-low Optical Power Detection in the Near Infrared

Abstract

Static characteristics of two different structured InAlGaAs/InAlAs superlattice avalanche photodiodes (SLAPDs) cooled by liquid nitrogen were evaluated at a wavelength of 1.5 μm. The dark current of the SLAPD having a thick superlattice layer of 0.504 μm was 5×10^-13 A. This was successively reduced by four orders of magnitude compared to that of the thin layer SLAPD of 0.231 μm at a breakdown voltage of around 20 V. The thickened layer was effective in suppressing tunneling dark current. An output current of 1.7×10^-12 A at a bias voltage of 15 V was measured for an optical input with a wavelength of 1.5 μm and a signal power of 1×10^-12 W. This showed a sharp distinction from the dark current.