(AlxGa1-x)2O3-based materials: Growth, properties, and device applications

In recent years, the (AlxGa1-x)2O3 materials have attracted intense research interest due to their considerable potentials in the fabrication of deep-ultraviolet optoelectronic and high-power electronic devices. Recent pioneering studies show that the (AlxGa1-x)2O3 materials possess high dielectric constants and breakdown electric fields, the high-density two-dimensional electron gas, and the large tunable bandgap. A high-density two-dimensional electron gas (1012 − 1013 cm-2) is observed in (AlxGa1-x)2O3/Ga2O3 heterostructures, which significantly enhances power handling capabilities of Ga2O3-based transistors. The detection wavelength of the peak photoresponsivity has been successfully modulated to 230 nm for deep-ultraviolet photodetectors fabricated from (AlxGa1-x)2O3 materials. The research of (AlxGa1-x)2O3 materials growth and device applications has manifested many interesting and exciting results in recent years. This article presents recent advances in structural and electronic properties, growth methods, thermal conductivity, two-dimensional electron gas, and device applications of (AlxGa1-x)2O3-based materials. The impact of growth conditions, substrates, and dopants on epitaxial relationships, crystalline quality, surface morphology, and phase segregation is discussed in detail. The band alignments, bandgap tailoring, and induced two-dimensional electron gas of (AlxGa1-x)2O3/Ga2O3 heterostructures are summarized and discussed. Finally, a brief overview of challenges and opportunities for (AlxGa1-x)2O3 materials is presented.