Deep-level transient-spectroscopy study of rhodium in indium phosphide

The electrical properties of rhodium-related defects in low-pressure metal-organic chemical-vapor-deposition-grown InP:Rh are investigated. Rh concentrations up to 1×${10}^{19}$ ${\mathrm{cm}}^{\mathrm{-}3}$ are achieved without formation of macroscopic ${\mathrm{Rh}}_{\mathit{x}}$ ${\mathrm{P}}_{\mathit{y}}$ precipitates. With deep-level transient spectroscopy, two Rh-related deep levels, RhA and RhB, are observed in p-InP:Rh having zero- and low-field activation energies of ${\mathit{E}}_{\mathit{V}}$+0.71 and ${\mathit{E}}_{\mathit{V}}$+0.62 eV, respectively. Optimization of the growth parameters allows for both traps to obtain electrically active concentrations up to 2×${10}^{15}$ ${\mathrm{cm}}^{\mathrm{-}3}$. Detailed capacitance transient investigations were undertaken to study the field dependence of the emission rates and the hole capture cross sections of both levels. The emission rate is found to be strongly field dependent for both levels. For RhA the experimental data are well fitted with a Poole-Frenkel model employing a three-dimensional square well potential of 7.5 nm. The field-enhanced emission of RhB can be explained by a Coulomb potential in combination with a phonon-assisted tunneling process. Evidence is given that RhA is the ${\mathrm{Rh}}^{3+/2+}$ deep acceptor level in InP caused by isolated substitutional Rh on In sites. Both traps are suited as compensating acceptors for the growth of semi-insulating InP. © 1996 The American Physical Society.