Magneto-optical studies of donor impurities under high pressure

Abstract

Magneto-optical studies are presented of the shallow donor states and cyclotron resonance of free carriers in n-InSb at hydrostatic pressures of up to 15 kbar. The deepest of the shallow donors shows an interaction with L-associated resonance states in the conduction band. The admixture of L-states permits intervalley coupling by a single TA-(L) phonon of energy of 35 cm⁻¹. Resonant metastable states of predominantly X-character also exist and, when these are occupied, the L- and Λ-like transitions involving the same donor disappear. Preliminary results for the donors in GaAs suggest that similar anticrossing effects occur between the deepest of the shallow donors and resonant states in the conduction band. Both the cyclotron resonance and impurity lines in InSb show a dramatic narrowing which can amount to almost an order of magnitude on increasing the pressure above 5 kbar and central cell structure can be observed on all three of the 1s-2p transitions observed in a magnetic field.

On leave from UNIPRESS, Warsaw, supported by SERC Visiting Fellowship.