Investigation of the electrical properties of Ho-doped InSe single crystal

Resistivity and Hall-effect measurements have been performed on Ho-doped InSe single crystal grown by the Bridman–Stockberger method. The mass ratios of Ho added to the starting melts were 25×10−4, 25×10−3: Ho added in order to obtain different Ho concentrations. We found the temperature dependence of the Hall mobility as μe∼T−1.26 for n-type InSe, μe∼T−0.24 for InSe:Ho0.0025 and μe∼T−1.03 for InSe:Ho0.025 samples at 140–View the MathML source. Impurity-energy levels calculated from ln(n/T3/2) vs 103/T plots for InSe at 30–90 and 100–View the MathML source are View the MathML source, and View the MathML source, for InSe:Ho0.0025 at 20–50 and 90–View the MathML source are View the MathML source, and View the MathML source, for InSe:Ho0.025 at 30–90 and 80–View the MathML source are View the MathML source, and View the MathML source, respectively. The low Ho doping cleans the impurities acting as acceptors between the layers and makes the compensating impurity levels inactive. But the high Ho doping behaves as an impurity in InSe.