Seebeck Coefficient Measurements on Micron-Size Single-Crystal Zinc Germanium Nitride Rods

II–IV-nitride compounds are tetrahedrally bonded, heterovalent ternary semiconductors that have recently garnered attention for their potential technological applications. These materials are derived from the parent III-nitride compounds; ZnGeN 2 is the II–IV-nitride analogue to the III-nitride GaN. Very little is known about the transport properties of ZnGeN 2 . In this work, we present Seebeck coefficient ( S ) data on 3-micron-diameter, 70-micron-long, single-crystal ZnGeN 2 rods, employing a novel measurement approach. The measurements of S show that the majority free carriers are electrons, and imply that the carrier gas is degenerate. Within a single-band model for the conduction band, a carrier concentration of order 10 19 cm −3 was estimated for a measured S = −90 μ V/K. Together with electrical transport measurements, a lower limit for the electron mobility is estimated to be ∼20 cm 2 /V-s. A discussion of this material as a thermoelectric is presented. The background level of free electrons in this unintentionally doped ZnGeN 2 is very near the predicted optimum value for maximum thermoelectric performance.