Characterization of Carbon-Doped GaAs Grown by Molecular Beam Epitaxy Using Neopentane as Carbon Source

Neopentane, C(CH3)4, has been successfully used as a new carbon source in the molecular beam epitaxial (MBE) growth of carbon-doped GaAs. The hole concentration, which agrees with the carbon concentration, increases with increasing cracking temperature in the temperature range above 700°C. The highest hole concentration obtained using neopentane is 1.6×1020cm-3. Optical and electrical properties of a MBE-grown C-doped GaAs layer with neopentane are comparable to those of a metalorganic molecular beam epitaxy (MOMBE) grown C-doped GaAs layer using TMG and solid arsenic and MBE-grown Be-doped GaAs. The maximum hole concentration of 1.6×1020cm-3increases to 2.5×1020cm-3after annealing at 400^°C for 1 h in N2ambient. This is due to removal of hydrogen which passivates carbon acceptors in the as-grown GaAs.