We present the research efforts to achieve effective n-type doping in gallium oxide (Ga2O3), an ultrawide bandgap semiconductor, grown by metal-organic chemical vapor deposition (MOCVD). The application of semiconductors for power electronics requires wide and ultrawide bandgap materials that can be doped to create higher electron (n-type) or hole (p-type) densities. Ga2O3, with a bandgap of 4.9 eV, is an emerging and promising material. The bandgap of Ga2O3 is much higher than other wide bandgap material that have been adopted by or in the process of adoption by the industry for power electronics. However, the doping of Ga2O3 has some challenges; one there is no effective p-type dopant available, second the n-type doping result in low electron density and mobility, particularly, in its growth on sapphire substrate. Co-doping schemes were investigated to achieve effective doping in many other material systems. Silicon (Si) and indium (In) co-doping in Ga2O3 using different growth sequences has been reported. It has been observed that in other material systems Indium acts as a surfactant and the use of In and Si has resulted in higher density and mobility of the electrons, however there is no comprehensive study that has been reported. Our work systematically investigates the mechanism of electron density enhancement and mobility under different schemes of In-Si co-doped Ga2O3. Ga2O3 layers co-ped with Si and In exhibit high conductivity, with both silicon and indium contributing to improved electrical properties, that will result in improved performances of the devices. Additionally, the co-doping effects in Ga2O3 extend to structural and optical improvements, making the semiconductor materials desirable for various other applications.
Tahir et al. (Thu,) studied this question.