Growths and diffusions for InGaAs/InP single-photon avalanche diodes

In this paper we discuss some of the main characteristics and limitations of the fabrication process for InGaAs/InP single-photon avalanche diodes. The effects of minimum doping levels during semiconductor growths and the influence of wafer miscut on the dopant incorporation are analyzed with the support of experimental measurements on test wafers. The Zinc diffusion process is thoroughly analyzed and here we present and compare experimental results from diffusion tests at different wafer temperatures and precursor gas flows. In addition, double Zinc diffusion tests at high and low temperatures are discussed. Finally, the effects of the mask aperture on the Zinc diffusion depth have been measured, showing opposite trends at high and low diffusion temperatures.