Two-probe Electrical and Thermal Transport Measurements on 50-micron Long Single Crystal ZnGeN$_{2}$ Rods

While many modern electrical devices are based on III-nitride semiconductors such as GaN, these devices have some challenges related to the strong polarity of the wurtzite crystal structure and a difficulty in doping them p-type. ZnGeN$_{2}$ is a II-IV-nitride analog to GaN, and the two share very similar crystal structures, lattice parameters, and band-gap energies. ZnGeN$_{2}$ has a number of distinctly different predicted properties, however; in particular, its doping and defect properties and lower spontaneous polarization coefficients. So far, the electrical transport properties of ZnGeN$_{2}$ are not well studied. Recently, high quality, 50-micron long single crystal rods have been grown by a vapor-liquid-solid method. Electrical transport measurements are difficult on such small crystals. In this work, we will present a novel sample stage designed to perform 2-probe electrical measurements under the influence of a temperature gradient on these small crystals, enabling measurements of Seebeck coefficient and resistance. We will discuss modeling of Seebeck coefficient data for ZnGeN$_{2}$ and the design, fabrication, and performance of sample stage prototypes.