Abstract
We present uniaxial-stress experiments performed on the direct and indirect exciton spectrum of GaP. Two direct transitions ( and ) and three indirect phonon-assisted transitions (LA, TA, and TO phonon modes) have been investigated at 77 and 4.2°K, respectively. Very-high-stress conditions have been achieved in this work (kbar) which correspond to an axial deformation , reaching the elastic limit of the material. We have been able to determine all linear and nonlinear deformation potentials that describe the stress dependence of the topmost valence bands ( and ) and of the lowest minima of the conduction band ( and ). The stress splitting of the valence band is produced by (i) the orbital-strain interaction, which is described by two deformation potentials and , and (ii) the stress-dependent spin-orbit interaction which is described by two extra parameters and . We find eV, eV, eV, and eV. The effect of hydrostatic deformation is again interpreted in terms of two deformation potentials (orbital-strain interaction) and (strain-dependent spin-orbit interaction). They combine with two hydrostatic deformation potentials for the conduction band and to give the net pressure coefficients. We find eV, eV, and eV. The shear deformation potential of the indirect minimum of the conduction band has been obtained from the same series of measurements. We find eV. Lastly, the stress-induced coupling between the lowest minimum of the conduction band () and the next higher minimum () has been observed, and is described by a single deformation potential . We find eV.
- Received 17 March 1978
DOI:https://doi.org/10.1103/PhysRevB.19.2209
©1979 American Physical Society