1. See, for example, Capasso, F., Mater. Res. Soc. Bull.
16, 23 (1991), and references therein.
McKinley, J. T., Hwu, Y., Rioux, D., Terrasi, A., Zanini, F., Margaritondo, G., Debska, U., and Furdyna, J. K., J. Vac. Sci. Technol. A
8, 1917 (1990), and references therein.
Maierhofer, Ch., Zahn, D. R. T., Evans, D. A., and Horn, K., in Proc. 3rd Int. Conf. on the Formation of Semiconductor Interfaces, Rome, Italy, May 6–10, 1991 Appl;.Surf. Sci. (in press).
Shen, T.-H., Elliott, M., Williams, R. H., and Westwood, D., Appl. Phys. Lett.
58, 842 (1991).
Sorba, L., Bratina, G., Ceccone, G., Antonini, A., Walker, J.F., Micovic, M., and Franciosi, A., Phys. Rev. B
43, 2450 (1991);
Ceccone, G., Bratina, G., Sorba, L., Antonini, A., and Franciosi, A., Surf. Sci.
251–252, 82 (1991).
Baroni, S., Resta, R., Baldereschi, A., and Peressi, M., in Spectroscopy of Semiconductor Microstructures, Fasol, G., Fasolino, A., and Lugli, P., eds. (Plenum Publ. Corp., New York, 1989), p. 251.
Muñoz, A., Chetty, N., and Martin, R., Phys. Rev.
41, 2976 (1990).
Peressi, M., Baroni, S., Resta, R., and Baldereschi, A., Phys. Rev. B
43, 7347 (1991).
Bratina, G., Sorba, L., Antonini, A., Vanzetti, L., and Franciosi, A., J. Vac. Sci. Technol. B
9, 2225 (1991);
Sorba, L., Bratina, G., Antonini, A., Franciosi, A., Tapfer, L., Migliori, A., and Merli, P., Phys. Rev. B (to be published).
Strite, S., Ünlü, M.S., Adomi, K., and Morkoç, H., Appl. Phys. Lett.
56, 1673 (1990) and references therein.
Bratina, G., Sorba, L., Antonini, A., Biasiol, G., and Franciosi, A., Phys. Rev. B (in press).
12. An alternate growth procedure was also examined in which no As flux was employed during Ge deposition (background pressure during deposition <5×10−10 Torr). XPS-determined interface layer thickness and band offsets were found to be consistent, within experimental uncertainly, for samples fabricated with the two deposition procedures, although the two procedures corresponded to qualitatively different RHEED patterns from the Ge layer.
Strite, S., Unlu, M.S., Adomi, K., Gao, G.-B., Agarwal, A., Rockett, A., Morkoç, H., Li, D., Nakamura, Y., and Otsuka, N., J. Vac. Sci. Technol. B
8, 1131 (1990) and references therein.
14. The RHEED pattern changes in the absence of an As flux, although none of the other results discussed here is affected . For example, a 2×2 RHEED pattern is observed during Ge growth at 360°C on GaAs (OOl), in agreement with the results of Ref. 13.
15. See, for example, Kraut, E.A., in Heterojunction Band Discontinuities : Physics and Device Applications, edited by Capasso, F. and Margaritondo, G. (North-Holland, Amsterdam, 1987), and references therein.
16. This in agreement with most recent photoemission determinations of the valence band offset, such as those by Hirakawa, K., Hashimoto, Y., and Ikoma, T., Appl. Phys. Lett.
57,. 2555 (1990), who found δEv=0.44±0.05eV,
Yu, E. T., Chow, D. H., and McGill, T. C., J. Vac. Sci. Technol. B
7, 391 (1989), who found δEV=0.46±0.07eV,
Waldrop, J. R., Grant, R. W., and Kraut, E. A., J. Vac. Sci. Technol. B
5, 1209 (1987), who found δEV=0.36–0.46eV, and
Katnani, D. and Bauer, R. S., Phys. Rev. B
33, 1106 (1986), who reported δEV=0.39±0.07eV. Optical determinations of the valence band offsets by
Dawson, P., Moore, K. J., and Foxon, C. T., Proc. SPIE
792, 208 (1987), and
Wolford, D. J., in Proc. of the 18th International Conference of the Physics of Semiconductors, edited by Engstrom, O. (World Scientific, Singapore, 1987), p. 1115, yielded values of 0.53–0.56eV so that in principle a small systematic discrepancy may exist between photoemission and optical determinations of the offset.
17. The latter obviously is the actual growth mode in the absence of the group IV interface layer, and is therefore likely to remain the actual growth mode also at the lowest Ge or Si coverages explored, but for higher Ge or Si thicknesses the situation may be different. See Bringans, F. D., Olmstead, M. A., Ponce, F. A., Biegelsen, D. K., Kruaoc, B. S., and Yingling, R. D., J. Appl. Phys.
64, 3472 (1988) and references therein.
McKinley, J. T., Hwu, Y., Koltenbah, B. E. C., Margaritondo, G., Baroni, S., and Resta, R., J. Vac. Sci. Technol. B (in press), and Proc. 3rd Int. Conf. on the Formation of Semiconductor Interfaces, Rome, Italy, May 6–10, 1991; Appl. Surf. Sci. (in press).