p-type conduction in ion-implanted amorphized Ge

The electrical transport properties of n-type crystalline-Ge amorphized by ion implantation have been determined by resistivity and Hall effect measurements in the 64–255 K temperature range. Amorphous layer was realized by implanting Ge+ ions in Ge single crystal maintained at ∼77 K at fluences above the amorphization threshold. The samples exhibited a surprising lower sheet resistance with respect of un-implanted crystalline Ge, resulting from positive charge carriers and very high mobility. Experimental observations are consistent with a p-type conduction induced by surface states and a high mobility channel at the amorphous-crystal interface.