Structural, Optical, and Electrical Properties of RF Magnetron Sputtered Germanium Dioxide Thin Films*

Rutile germanium dioxide (GeO₂), an ultra-wide bandgap (UWBG) oxide semiconductor, has recently gained attention for high-power applications due to its excellent thermal and electrical properties [1,2]. In this work, GeO₂ thin films were deposited using radio frequency magnetron sputtering (RFMS) on r-plane Al₂O₃substrates. Following sputtering, post-deposition annealing (PDA) was performed. To fabricate the van der Pauw geometry test structures, Ni/Au contacts were deposited via metal shadow mask patterning by e-beam evaporation. To study the chemical, optical, and structural nature of the films, x-ray diffraction (XRD), atomic force microscopy (AFM), and optical spectroscopy (UV−vis) were used. Hall measurements were performed to assess the film’s electrical properties. Results correlating the effect of PDA with the structural, optical, and electrical properties of the GeO₂ thin films will be presented. This work provides further understanding towards the structural and electrical properties of polycrystalline GeO₂ thin films for future UWBG device applications.

 

[1] Chae, S. et al., Appl. Phys. Lett. 114, 102104 (2019).

[2] Chae, S. et al., Appl. Phys. Lett. 117, 102106 (2020).