THERMAL-STABILITY OF HIGHLY SB-DOPED MOLECULAR-BEAM EPITAXY SILICON GROWN AT LOW-TEMPERATURES - STRUCTURAL AND ELECTRICAL CHARACTERIZATION

The structural and electrical properties of highly Sb-doped molecular beam epitaxy grown silicon have been investigated as function of rapid thermal annealing (RTA) temperature. Doping levels of 3X10(20) cm(-3) were obtained using low, temperature epitaxy (LTE) performed at a growth temperature of 300 degrees C. Ion channeling and transmission electron microscopy (TEM) measurements showed that the as-grown samples were of very high quality. The combination of Hall-effect profiling and Rutherford backscattering spectroscopy revealed an electrically active Sb fraction of 0.8. Short time RTA processing improved the electron mobility and the activation: RTA at 600 degrees C for 10 s yielded unity activation and RTA at 800 degrees C gave mobilities matching phosphorus doped bulk values, thus significantly exceeding previously reported values for highly doped LTE material. A degradation of the crystalline quality was observed for higher RTA temperatures: RTA at 2000 degrees C for 10 s reduced both the Sb-substitutional fraction and electrical activation to 0.6 due to precipitation of Sb, and lead to the formation of a high density of dislocation loops as observed by TEM. A large fraction of the precipitates decorated these dislocation loops. Mesa isolated diodes were fabricated to evaluate the use of LTE material for device production. Current-voltage measurements on these diodes revealed high quality junctions with low reverse currents and near-ideal forward characteristic.