High Pressure Far-Infrared Magnetooptical Studies of Sn and S Donors in GaAs

The diamond anvil cell technique is applied for magneto-optical far-infrared transmission experiments with LPE grown GaAs:Sn. The 1s-2p(+) intra-shallow-Γ-donor transition is investigated as a function of high hydrostatic pressure for Sn and residual S donors. Both donors are shallow up to 30 kbar. Above this pressure both donors become deep and shallow donor absorption is persistently bleached due to deep non-metastable (non DX-like) states of the donors entering the gap of GaAs.