Shallow donorlike impurity states in n-type InP in magnetic field and under hydrostatic pressure.

Abstract

Hall-coefficient and transverse magnetoresistivity measurements performed in magnetic fields up to 18 T and hydrostatic pressures up to 16.5 kbar reveal several features of the behavior of shallow donorlike impurity states in n-type InP with impurity concentrations spanning the metal-insulator transition (2.2\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$\ensuremath{\lesssim}${\mathrm{N}}_{\mathrm{d}}$-${\mathrm{N}}_{\mathrm{a}}$\ensuremath{\lesssim}6.2\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$). At atmospheric pressure, the variation of the binding energy of the shallow donors versus magnetic field was found to follow the predicted hydrogenic behavior with increasing effects of electron correlations (screening of the long-range Coulomb potential) and overlap of impurity wave functions as the donor concentration increased. With increasing pressure, the binding energy increased only slightly up to \ensuremath{\sim}10 kbar, then much more strongly at 10 kbar\ensuremath{\lesssim}P\ensuremath{\lesssim}16.5 kbar. This behavior, which additionally depended on the actual magnetic field strength, showed very close similarities to effects observed earlier in other III-V compounds and suggests an increasing influence of the short-range localized impurity potential.