Atomically control of surface morphology in Ga2O3 epi-layers with high doping activation ratio

In this study, a two-step surface treatment process combined with pulsed laser deposition (PLD) was developed for obtaining high quality Ga2O3 epi-layers with atomic flat interface and effectively activated dopants. The results showed that semi-insulating Fe-doped Ga2O3 thin film with terraced atomic steps was successfully obtained via the PLD for the first time. The carrier concentration down to 4.39 × 107 cm−3 and square resistance up to 2.26 × 1011 Ω/□ made it comparable to commercial Fe-doped single crystals. Another Sn-doped epi-layer with terraced atomic steps was then deposited on the Fe-doped layer, exhibiting a carrier concentration of 2.01 × 1020 cm−3 and an Sn activating ratio of 41.1%, which broke the bottleneck of low activating ratio in metal organic vapor-phase epitaxy or molecular beam epitaxy. These results demonstrate a simple method to get atomically flat interfaces and tunable charge carriers in Ga2O3 epi-growth and provide a potential material basis for Ga2O3 high electron mobility transistor.