c-Axis Orientation of Sputtered ZnO Films

Abstract

Piezoelectric tests on thin polycrystalline films of sputtered ZnO have shown that the c‐axis polarity is dependent on the substrate material. Evidence suggests that the heat conductivity of the substrate is the bulk physical property controlling this effect. Two different c‐axis polarities might be expected, since it has already been observed that the two polar ends of ZnO have different properties. Correlation of these piezoelectric data with existing crystallographic conventions shows that substrates with large heat conductivity cause the ZnO to grow with the Zn face next to the Au layer evaporated onto each substrate before deposition.