Optical response time of In0.53Ga0.47As/InP avalanche photodiodes

Abstract

Heterojunction In0.53Ga0.47As/InP avalanche photodiodes have recently been observed to have a response to long-wavelength optical pulses which contains both fast and slow components. We present evidence that the slow response is limited by charge pile-up at the semiconductor heterointerface. We find that the speed of response depends on the degree of compositional grading in the heterointerface region. The response time can be significantly reduced for compositional grading lengths of greater than 600 Å depending on the doping and depletion region width in the In0.53Ga0.47As layer.