Theoretical investigation of optical intersubband transitions and infrared photodetection in β-(AlxGa1 − x)2O3/Ga2O3 quantum well structures.

We provide theoretical consideration of intersubband transitions designed in the ultra-wide bandgap aluminum gallium oxide [(AlxGa1 − x)2O3]/gallium oxide (Ga2O3) quantum well system. Conventional material systems have matured into successful intersubband device applications such as large-area quantum well infrared photodetector (QWIP) focal plane arrays for reproducible imaging systems but are fundamentally limited via maximum conduction band offsets to mid- and long-wavelength infrared applications. Short- and near-infrared devices are technologically important to optical communication systems and biomedical imaging applications but are difficult to realize in intersubband designs for this reason. In this work, we use a first-principles approach to estimate the expansive design space of monoclinic β-(AlxGa1 − x)2O3/Ga2O3 material system, which reaches from short-wavelength infrared (1–3 μm) to far infrared (>30 μm) transition wavelengths. We estimate the performance metrics of two QWIPs operating in the long- and short-wavelength regimes, including an estimation of high room temperature detectivity (∼1011 Jones) at the optical communication wavelength λp = 1.55 μm. Our findings demonstrate the potential of the rapidly maturing (AlxGa1 − x)2O3/Ga2O3 material system to open the door for intersubband device applications. [ABSTRACT FROM AUTHOR]