Vogt, S.; Petersen, C.; von Wenckstern, H.; Schultz, T.; Koch, N.; Grundmann, M.: Zr doping in pulsed-laser-deposited α-Ga2O3 for device applications. Physical Review Applied 21 (2024), p. 064016/1-8
10.1103/PhysRevApplied.21.064016
Open Access Version
(available 01.07.2025)Abstract:
The feasibility of zirconium doping of α-Ga2O3 grown by pulsed laser deposition is demonstrated. Targets with different zirconium contents are used to adjust the zirconium content in the thin films. Therefore, a two-step growth process is utilized, where first an undoped α-Ga2O3 thin film is grown as a high-temperature buffer layer and the zirconium-doped α-Ga2O3 layer is subsequently deposited at a lower growth temperature. Highly conductive thin films are obtained with resistivities as low as 3.3 × 10−3 cm. An electron mobility as high as 38 cm2 V−1 s−1 is measured for a high free carrier density of 6.5 × 1018 cm−3. The crystallization in the α-phase was confirmed by x-ray diffraction measurements. Further, a strong influence of the growth temperature on the zirconium incorporation is observed, which can be explained by the increased desorption of volatile Ga2O3 suboxides at high growth temperatures. Depth-resolved x-ray photoelectron spectroscopy measurements were employed to investigate the doping profile in the thin films. They reveal a strongly depth-dependent incorporation of the zirconium, with a decreased incorporation towards the surface. First Schottky barrier diodes on zirconium-doped α-Ga2O3 thin films with rectification ratios as high as 8.5 orders of magnitude at ±3 V are presented.