Amorphous Silicon Films and Nanocolumns Deposited on Sapphire and GaN by DC Sputtering

Abstract

Sputtering is a deposition technique used to fabricate low‐cost silicon films on crystalline and amorphous substrates. Herein, the deposition of amorphous silicon films by DC sputtering on both sapphire and GaN/sapphire substrates is reported. Films are deposited using argon plasma with a pressure of 0.47 Pa at 30–60 W of DC power and different deposition temperatures from RT to 550 °C. The effect of different deposition conditions is investigated on structural quality, layer morphology, and optical properties of the layers. X‐ray diffraction measurements do not show any peak associated to crystalline silicon, while energy‐dispersive X‐ray demonstrates the presence of silicon in the layers. Silicon films deposited on sapphire show a compact morphology but the formation of silicon columns on GaN. On both substrates, the growth rate increases a factor of 3 with the applied DC power (50–150 nm h−1). Finally, the optical bandgap energy extracted from transmission measurements decreases from 2.40 to 2.10 eV with the DC power, due to the reduction of impurity incorporation. This work offers a low‐cost alternative for the deposition of amorphous compact silicon films and silicon nanocolumns at low temperature, for application in sensing, photonic, electronic, and photovoltaic devices.