Carrier Transport and Electrical Bandgaps in Epitaxial CrN Layers

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Abstract
The transport properties and electrical bandgap of nominally undoped 75‐nm‐thick CrN layers simultaneously grown on AlN(0001) and AlN(112) templates using plasma‐assisted molecular beam epitaxy are investigated. The layers grown on AlN(0001) and AlN(112) exhibit (111) and (113) surface orientations, respectively. All layers exhibit antiferromagnetism with a Néel temperature of K, observed by temperature‐dependent magnetic and electrical measurements. Hall‐effect measurements demonstrate n‐type semiconducting behavior across a wide temperature range from 4 to 920 K. At low temperatures ( K), the data show parallel conduction channels from a metallic impurity band and the conduction band. The carrier mobility exhibits a temperature dependence consistent with a nondegenerate semiconductor, governed by ionized‐impurity scattering below 400 K and phonon scattering above 400 K. An analysis of the temperature‐dependent carrier density between 300 and 920 K yields two activation energies associated with intrinsic conduction: 0.15 eV (with an uncertainty of eV), which we attribute to the fundamental bandgap, and 0.50 eV (with an uncertainty of eV) representing a higher energy transition.

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