Effect of a seed layer on microstructure and electrical properties of Ga2O3 films on variously oriented Si substrates

The realization of the free interface strain between a Ga2O3 material and a substrate is significantly critical to fulfill the requirements for the fabrication of high-quality Ga2O3 material. In this work, a seed layer (SL) was utilized to circumvent the interface strain issue for enhancing quality and reducing surface roughness. The smooth surface and high-quality Ga2O3 thin film on (100)-Si substrate can be achieved under the growth parameters of 700 °C and 6 mTorr. The as-annealed Ga2O3 thin films grown on variously oriented Si substrates host various microstructure and surface roughness due to the different lattice mismatches at interfaces. The differences in surface roughness of Ga2O3 thin films are greatly eliminated by the deposition of a SL of Ga2O3 thin film on Si substrate. The PL spectra of as-annealed Ga2O3 thin films consist of three peaks at UV and green emission regions. The green luminescence intensity is reduced through the deposition of a SL, indicating lower surface defects and oxygen vacancy concentration. The Ga2O3 thin film with a SL presents a small RMS, high quality and limited dark-current. The work offers a promising strategy to make Ga2O3 film with high-quality and smooth surface on Si for fabricating the functional devices. •The Ga2O3 films were deposited on (100)-, (110)- and (111)-Si substrates through the RF magnetron sputtering technique.•The annealing treatment was utilized to improve the crystallization quality of Ga2O3 film.•The Ga2O3 films on various Si substrates show different surface morphologies due to different interface lattice mismatch.•A seed layer is in favor of reducing surface roughness of Ga2O3 film and eliminating the impacts of substrate orientations.