High-pressure investigation of GaSb and ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{In}}_{\mathit{x}}$Sb/GaSb quantum wells

We report a high-pressure study of metal-organic-vapor-phase-epitaxially-grown bulk GaSb and ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{In}}_{\mathit{x}}$Sb/GaSb quantum wells. For photoluminescence experiments we have used a diamond-anvil cell with pressures up to 75 kbar, using the photoluminescence from bulk InP as a pressure gauge. For bulk GaSb we have measured the Γ-gap pressure coefficient as 1.64±0.03 times larger than that of InP. No bulk GaSb luminescence could be observed above the ${\mathit{L}}_{\mathit{c}}$-${\mathrm{\Gamma }}_{\mathit{c}}$ crossover. The Γ gap of the quantum well is found to have the same pressure coefficient as the bulk GaSb to within our ∼3% experimental error. This is understood essentially as a consequence of the material and electronic similarity of GaSb and ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{In}}_{\mathit{x}}$Sb (x∼15%). At higher pressure both the quantum well ${\mathit{L}}_{\mathit{c}}$ and ${\mathit{X}}_{\mathit{c}}$ conduction-band states are unambiguously observed. There is an ${\mathit{L}}_{\mathit{c}}$-${\mathrm{\Gamma }}_{\mathit{c}}$ crossover at 16 kbar, and then an ${\mathit{X}}_{\mathit{c}}$-${\mathit{L}}_{\mathit{c}}$ crossover at 43 kbar. These effects are discussed in relation to the hydrostatic- and shear-strain perturbations to the band structure. The quantum-well luminescence quenched at about ∼70 kbar, and this is interpreted as a phase change of the GaSb.