The Influence of Optical Excitation and Hydrostatic Pressure on the Conductivity of Doped GaAs, InP and (InGa) (AsP).

Resistivity and photoconductivity measurements have been made, using hydrostatic pressures up to 75 kb on localised states in some III - V semiconductors, including ones with transition metal ions present. The systems investigated were GaAs: Sn, GaAs: Cr: S, n - In[x] G[1-x] As[y] P[1-y], InP: Fe and GaAs: Cr. Many electronic transitions involving localised states (some deep in the band gap) appear to have anomolously high pressure coefficients. Possible explanations are discussed