CHARACTERIZATION OF CARBON-DOPED GAAS GROWN BY MOLECULAR-BEAM EPITAXYUSING NEOPENTANE AS CARBON SOURCE

Neopentane C(CH-3)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, increa ses with increasing cracking temperature in the temperature range abov e 700-degrees-C. The highest hole concentration obtained using neopent ane is 1.6 x 10(20) cm-3. Optical and electrical properties of a MBE-g rown C-doped GaAs layer with neopentane are comparable to those of a m etalorganic molecular beam epitaxy (MOMBE) grown C-doped GaAs layer us ing TMG and solid arsenic and MBE-grown Be-doped GaAs. The maximum hol e concentration of 1.6 X 10(20) cm-3 increases to 2.5 x 10(20) cm-3 af ter annealing at 400-degrees-C for 1 h in N2 ambient. This is due to r emoval of hydrogen which passivates carbon acceptors in the as-grown G aAs.