Photoresponse of Si1-xGex heteroepitaxial p-i-n photodiodes

A simulation study of spectral response, dark current and capacitance of Si 1-xGex heteroepitaxial p-i-n photodiodes as a function of thickness of the i-layer and Ge mole fraction has been performed. It has been found that the cut-off wavelength of the diodes increases from 1.12 to 1.50 mu m as the G e mole fraction (x) is increased From 0.0 to 0.75 and the photoresponse inc reases with the thickness of the absorbing i-layer. The simulated photoresp onse of p-i-n diodes is in good agreement with reported experimental data. The dark current is found to increase with Ge concentration and remains in the nA range for upto 30% Ge which corresponds to a cut-off wavelength of a pproximate to 1.3 mu m, extending the possibility of these devices in fiber optic communication applications. (C) 1999 Elsevier Science Ltd. All rights reserved.