CHARACTERIZATION OF ANNEALED HEAVILY C-DOPED P+-ALGAAS

This paper systematically analyzes the sources of the degradation of majority- and minority-carrier characteristics in annealed/as-grown heavily carbon-doped Al0.12-0.13Ga0.88-0.87As epilayers grown by metalorganic chemical vapor deposition. Hydrogen atoms in the as-grown epilayers act as acceptor killers for majority carriers with one-to-one correspondence but not as very effective recombination centers for minority carriers. The hydrogen atoms occupy bond-centered positions and relax the lattice contraction due to carbon doping by a ratio of about 2.5 X 10(-3) A per 10(20) cm-3 atoms. Post-growth annealing in nitrogen decreases these hydrogen atoms. On the other hand, annealing in a mixture of hydrogen and arsine increases the number of hydrogen atoms, but all the introduced hydrogen atoms do not necessarily act as acceptor killers. Sources other than hydrogen atoms, which are created by annealing above 600-degrees-C, and those of as-grown apparently act as both compensation centers for majority carriers and as very effective nonradiative recombination centers for minority carriers. These sources seem to relax the lattice contraction by the ratio of about 8 X 10(-3) A or less per 10(20) cm-3 majority-carrier decrease and may have structures containing interstitial carbon.