Hydrogen Passivation of Carbon Acceptors in AlAs Grown by Atomic Layer Epitaxy

Abstract
Hydrogen incorporation and passivation of the carbon acceptors in AlAs grown by atomic layer epitaxy are examined. It is shown that about the same amount of hydrogen as that of carbon impurities are contained in the epilayer, whereas the hole concentration is more than two orders of magnitude lower than the carbon concentration. The carbon acceptor bonds to the hydrogen and is passivated by it. Annealing, especially in nitrogen, removes the hydrogen and causes recovery of the electrical activation of carbon acceptors. The hydrogen is found to originate from the alkyl groups of trimethylaluminum (TMA), not from arsine or the carrier gas.