Deep-ultraviolet transparent conducting SrSnO via heterostructure design.

Exploration and advancements in ultrawide bandgap (UWBG) semiconductors are pivotal for next-generation high-power electronics and deep-ultraviolet (DUV) optoelectronics. Here, we used a thin heterostructure design to facilitate high conductivity due to the low electron mass and relatively weak electron-phonon coupling, while the atomically thin films ensured high transparency. We used a heterostructure comprising SrSnO/La:SrSnO/GdScO (110), and applied electrostatic gating, which allow us to effectively separate charge carriers in SrSnO from dopants and achieve phonon-limited transport behavior in strain-stabilized tetragonal SrSnO. This led to a modulation of carrier density from 10 to 10 cm, with room temperature mobilities ranging from 40 to 140 cm V s. The phonon-limited mobility, calculated from first principles, closely matched experimental results, suggesting that room temperature mobility could be further increased with higher electron density. In addition, the sample exhibited 85% optical transparency at a 300-nm wavelength. These findings highlight the potential of heterostructure design for transparent UWBG semiconductor applications, especially in DUV regime.