1.3 MU-M PHOTORESPONSIVITY IN SI-BASED GE1-XCX PHOTODIODES

Ge1-xCx/Si heterostructure photodiodes with nominal carbon percentages (0 less than or equal to x less than or equal to 0.02), which exceed the solubility limit, were grown by solid source molecular beam epitax y on n-type (100) Si substrates. The p-Ge1-xCx/n-Si photodiodes were f abricated and tested. The p-G(1-x)C(x)/n-Si junction exhibits diode re ctification with a reverse saturation current of about 10 pA/mu m(2) a t -1 V and high reverse: breakdown voltage, up to -80 V. A significant reduction in diode reverse leakage current was observed by adding C t o Cel but these effects saturated with more C. Photoresponsivity was o bserved from these Si-based p-Ge1-xCx/n-Si photodiodes at a wavelength of greater than or equal to 1.3 mu m. compatible with fiber optic wav elengths. External quantum efficiency of these thin surface-normal pho todetectors was measured up to 2.2%, which decreased as the carbon per centage was increased. (C) 1998 Americans Institute of Physics.