Ultrathin n-type doping in β -Ga2O3 using SiO2 solid dopant source

We report an n-type doping method for beta-gallium oxide (β-Ga2O3) using amorphous silicon and silicon dioxide (SiO2) as solid sources. The a-Si and SiO2 are deposited by plasma-enhanced chemical vapor deposition. A rapid thermal annealing process at 1000 °C is used to drive in the silicon dopant into the epitaxial β-Ga2O3 layer. The a-Si and SiO2 are wet-etched to reveal the bare gallium oxide surface with a surface doping of ≈1019 cm−3. The measured sheet resistance and contact resistance are 35 Ω/sq and 0.1 Ω mm, respectively, proving the efficacy of the doping method. This proposed method can be a cost-effective and simpler alternative to ion implantation. The method can also be used for selective area doping for lateral and vertical field effect transistors.