Low Resistance Ohmic Contact for ZnSb Thin Film

To further improve the performance and power density of thermoelectric devices, the size of the device needs to be scaled down from macroscale to microscale. Different from the macroscale device, the specific contact resistivity rho (c) of the metal contact to the microscale device becomes a key point to the device's efficiency. In this study, a P type ZnSb thin film was deposited on glass substrate using a radio frequency magnetron sputtering system, followed by annealing at 325A degrees C in an Ar atmosphere. X-ray diffraction, scanning electron microscopy, and the Hall measurement system were utilized for characterization of the ZnSb. The ohmic contact properties of metallic Co and Mo on the annealed ZnSb thin films were investigated, indicating that metallic Co has a lower specific contact resistivity rho (c) to ZnSb. The effect of a diluted HCl-etch prior to Co electrode deposition was also studied. The results show that a HCl-etch is effective for the reduction of the rho (c). The dependence of rho (c) on the annealing temperature was also studied. Through HCl-etch and annealing at 200A degrees C, specific contact resistivity rho (c) as low as 10(-7) Omega cm(2) is successfully obtained on the Co electrode, providing a good method to fabricate a highly efficient ZnSb-based micro device.