Reduced pressure chemical vapor deposition of Ge thick layers on Si(0 0 1), Si(0 1 1) and Si(1 1 1)

We have carried out an in-depth structural study of Ge thick layers grown using the so-called “LT/HT” approach on Si(0 0 1), Si(0 1 1) and Si(1 1 1) wafers. The low temperature (400 °C) adopted for the first Ge layer plastically relaxes the strain in the Ge film without 3D islanding. The high temperature (750 °C) used for the growth of the second, topmost, Ge layer lowers the dislocation density and reduces the overall deposition time. High temperature thermal cycling (in-between 750 and 890 °C) was called upon to further reduce the amount of defects in the layers. Ge growth rates on (0 0 1) were consistently higher than the ones on (1 1 1), which were themselves higher than on (0 1 1) (be it at 400 °C, 100 Torr or at 750 °C, 20 Torr). The surfaces of Ge (0 0 1) layers were rather flat, as attested by their small root mean square (rms) roughness and Z ranges (