EFFECTS OF HYDROGENATION OF DEEP AND SHALLOW LEVELS IN ALGAAS GROWN BY MBE

The effects of treatments with hydrogen plasma (hydrogenation) and of subsequent annealing (dehydrogenation) on the photoluminescence effici ency and on the net donor and deep level concentrations in AlxGa1-xAs grown by molecular beam epitaxy are reported. It is shown that hydroge nation results in the passivation of the shallow donors, whose electri cal and optical activities are partially restored after dehydrogenatio n. It is also shown that deep centres such as ME5, ME6 and DX are pass ivated by hydrogenation. The DX centre is restored to a significant ex tent by dehydrogenation, whereas the ME5 and ME6 defects are reactivat ed only to a minor extent. The strong increase in the PL efficiency ob served after hydrogenation and its dependence on growth temperature ar e shown to be consistent with the dominant role of the ME5 and ME6 cen tres on the non-recombination process in AlxGa-xAs.