Hopping conduction in partially compensated doped silicon.

We have measured the dc electrical resistance of partially compensated (5\char21{}50 %) ion-implanted Si:P,B (both n and p type), over the temperature range 0.05\char21{}30 K. The temperature behavior is consistent with the prediction of the model for variable-range hopping (VRH) with a Coulomb gap \ensuremath{\rho}(T)=${\mathrm{\ensuremath{\rho}}}_{0}$exp(${\mathit{T}}_{0}$/T${)}^{1/2}$ over a temperature range 6.5${\mathit{T}}_{0}$/T24. We observe deviations from this behavior at our high- and low-temperature extremes. In the low-temperature region, the resistivities show a stronger temperature dependence than the Coulomb-gap model prediction. The high-temperature deviation appears consistent with a transition from Coulomb-gap VRH to Mott VRH.