<title>Annealing effects on heavily C-doped GaAs and InGaAs films</title>

Abstract

The hole carrier concentration of heavily carbon doped GaAs epilayers (4.7 X 10<SUP>19</SUP> and 9.8 X 10<SUP>19</SUP> cm<SUP>-3</SUP>) was increased and the mobility and lattice parameter were decreased by rapid thermal annealing silicon nitride capped samples at temperatures from 500 to 900 degree(s)C. For the more heavily doped sample, the hole concentration, mobility, and lattice mismatch decreased with increasing annealing temperature for annealing temperatures higher than 700 degree(s)C, but the hole concentration and mismatch were still larger than those of the as grown samples. Two heavily carbon doped InGaAs samples (2.35 X 10<SUP>19</SUP> cm<SUP>-3</SUP> and 2.05 X 10<SUP>19</SUP>) with low In mole fractions (1% and 8%) were furnace annealed with or without silicon nitride caps in H<SUB>2</SUB> containing 0.3% AsH<SUB>3</SUB> over the temperature range 500 - 800 degree(s)C. The changes observed for the capped samples were similar to those observed for the RTA annealed GaAs films, but for the uncapped samples the changes in the carrier concentration, mobility, and lattice parameter were for the most part much smaller. The only exception is the large increase in the lattice parameter at the highest annealing temperatures in the films containing 1% In. SIMS results showed that annealing produced no change in the C concentration or distribution, but the hydrogen concentration decreased in all samples except the uncapped films annealed in AsH<SUB>3</SUB>. We attribute the low temperature (&lt;EQ 700 degree(s)C) results in all but the uncapped samples annealed in AsH<SUB>3</SUB> to the removal of hydrogen which had passivated the carbon acceptor.