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 gro wth temperature of 300 degrees C. Ion channeling and transmission elec tron microscopy (TEM) measurements showed that the as-grown samples we re 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 m obility and the activation: RTA at 600 degrees C for 10 s yielded unit y activation and RTA at 800 degrees C gave mobilities matching phospho rus doped bulk values, thus significantly exceeding previously reporte d values for highly doped LTE material. A degradation of the crystalli ne quality was observed for higher RTA temperatures: RTA at 2000 degre es C for 10 s reduced both the Sb-substitutional fraction and electric al activation to 0.6 due to precipitation of Sb, and lead to the forma tion of a high density of dislocation loops as observed by TEM. A larg e fraction of the precipitates decorated these dislocation loops. Mesa isolated diodes were fabricated to evaluate the use of LTE material f or device production. Current-voltage measurements on these diodes rev ealed high quality junctions with low reverse currents and near-ideal forward characteristic.