CARBON ACCEPTORS PASSIVATED WITH HYDROGEN AND THE SEARCH FOR CARBON DONORS IN HIGHLY DOPED GAAS C

Highly carbon doped p-type GaAs grown by MOVPE shows infrared absorption lines from localized vibrational modes of C(As) acceptors and passivated H-C(As) pairs. A comparison with samples grown by MOMBE shows that an unassigned line at 563 cm-1 is due to a mode of H-C(As) pairs, although an isotopic analogue from D-C(As) pairs in plasma-treated samples has not been detected. The important new result is the demonstration that the line cannot be due to C(Ga) donors, and so there is still no evidence for the amphoteric behaviour of carbon impurities in GaAs.