Efficient high-speed near-infrared Ge photodetectors integrated on Si substrates

L. Colace, G. Masini, G. Assanto, H.-C. Luan, K. Wada, and L. C. Kimerling

Appl. Phys. Lett. 76, 1231-1233 (2000)


We have fabricated Ge/Si heterojunction photodetectors with high responsivities of 550 mA/W at 1.32 and 250 mA/W at 1.55, and time responses shorter than 850ps. High quality Ge was epitaxially grown on Si using ultrahigh vacuum/chemical-vapor-deposition followed by cyclic thermal annealing. The beneficial effect of the post-growth thermal annealing on the electrical properties of Ge epilayers, due to the reduction of threading dislocation densities, is confirmed by the dramatic enhancement of the performance of the photodetectors.