Effects of annealing ambient on the electrical properties in heavily C‐doped p⁺‐AlGaAs

The thermal behavior of the carrier concentration and the lattice constant in heavily carbon‐doped p⁺‐AlGaAs epilayers grown by metalorganic chemical vapor deposition are dramatically dependent on the annealing ambient at temperatures between 500 and 700 °C. Annealing in a hydrogen and arsine mixed gas ambient decreases the carrier concentration and increases the lattice constant. On the other hand, annealing in a hydrogen gas ambient increases the carrier concentration and decreases the lattice constant between 500 and 600 °C, which is consistent with our previous data for annealing in a nitrogen gas ambient. However, the carrier concentration after annealing at 700 °C is a little lower in hydrogen than in nitrogen. The above behavior of the carrier concentration and the lattice constant is well explained by incorporating and removing the hydrogen atoms in the epilayers during annealing.