PRESSURE DEPENDENCE OF NEAR-EDGE (5 K) RECOMBINATION IN HIGH-PURITY III-V MATERIALS.

PL, PLES, and time-resolved PL have been studied in high-purity n-type GaAs and InP at 5 K and hydrostatic pressures of up to 80 kbar. Fast, sharp direct-edge PL arises from free and bound excitons and BA transitions. Above 41. 5 kbar GaAs band structure becomes indirect; slower X//1-gap transitions resemble n-type GaP and reveal multiple donors. Excitons remain shallow and follow the gaps, thus giving precise GAMMA //1 and X//1 dependences on pressure (10. 74 and minus 1. 34 meV/kbar) and accurate band and level crossings. New indirect band gaps are established for GaAs.