Theoretical investigation of optical intersubband transitions and infrared photodetection in β-(Al_xGa_(1-x))_2O_3/Ga_2O_3 quantum well structures

摘要

We provide theoretical consideration of intersubband transitions designed in the ultra-wide bandgap aluminum gallium oxide [(Al_xGa_(1-x))_2O_3]/gallium oxide (Ga_2O_3) 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-(Al_xGa_(1-x))_2O_3/Ga_2O_3 material system, which reaches from short-wavelength infrared (l-3μm) to far infrared (＞30μm) 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 (～10~(11) Jones) at the optical communication wavelength λ_p= 1.55μm. Our findings demonstrate the potential of the rapidly maturing (Al_xGa_(1-x))_2O_3/Ga_2O_3 material system to open the door for intersubband device applications.