Metal-Ge-Si heterostructures for near infrared light detection

L. Colace, G. Masini, F. Galluzzi, G. Assanto, C. Capellini, L. Di Gaspare, E. Palange, and F. Evangelisti

J. Vacuum Sci. Tech. B 17, 465-467 (1999)


We report on Ge Schottky photodiodes epitaxially grown on Si (100) exhibiting a good responsivity in the near infrared up to 1.55 micron. The Ge epitaxial layers, grown by UHV-CVD, were deposited in two steps differing by the substrate temperature. With this procedure it was possible to obtain films thicknesses comparable with light penetration depth in the 1.3-1.6 micron range. The photodiodes have a photocurrent which increases as a function voltage bias, reaching a maximum responsivity of 0.12 A/W at 1.3 micron under a reverse bias of 4V. The leakage current density at the saturation voltage is 1nA/mm2. The results show that the proposed approach is promising for the fabrication of 1.3 -1.55 micron near infrared photodetectors integrated on silicon chips.