Deposition of Thermoelectric CrN Thin Films Using Bipolar HiPIMS

Sammanfattning

Conventionally, thermoelectric CrN thin films are deposited with direct current magnetron sputtering at 600 – 700 °C. Herein, high-power impulse magnetron sputtering (HiPIMS) is used to deposit both p-type and n-type CrN thin films at 200 °C growth temperatures. The transition occurred at a reactive gas flow ratio of 50 %. The Seebeck coefficient (S) increased from -27 μV/K to +76 μV/K, while the lattice parameter for the CrN (111) peak increased from 2.363 Å to 3.393 Å. Increasing the peak current led to decreased S: -37 μV/K was reached using 10 A (~0.49 A/cm2) of peak current. Furthermore, the influence of the reversed polarity pulse in bipolar HiPIMS was investigated. Increased voltage led to decreased resistivity, but no improvement could be seen in the Seebeck coefficient.