Pressure dependence of shallow bound states in gallium arsenide

Photoluminescence and PL-excitation of high-purity n-type GaAs is reported at He temperatures and hydrostatic pressures of up to 80 kbar in diamond anvil cells. At low pressures intense PL aises from direct-gap free and bound excitons and band-to-acceptor transitions. Band structure becomes indirect at 41.3 kbar and spectra resemble n-type GaP. Weak indirect (X1c)-gap recombination attributable to donor-bound-excitons and free excitons is identified. All bound states remain shallow and follow their band edges, thus giving the most precise Γ1c-Γ15v and X1c-Γ15v gap dependences on pressure (10.73 and -1.34 meV/kbar, respectively) yet reported. New indirect band gaps are derived for GaAs at atmospheric pressure. © 1985.