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 CAs acceptors and passivated H-CAs pairs. A comparison with samples grown by MOMBE shows that an unassigned line at 563 cm-1 is due to a mode of H-CAs pairs, although an isotopic analogue from D-CAs pairs in plasma-treated samples has not been detected. The important new result is the demonstration that the line cannot be due to CGa donors, and so there is still no evidence for the amphoteric behaviour of carbon impurities in GaAs.