The wide band gap semiconductor κ-Ga2O3 and its aluminum and indium alloys have been proposed as promising materials for many applications. One of them is the use of inter-sub-band transitions in quantum-well (QW) systems for infrared detectors. Our simulations show that the detection wavelength range of nowadays state of the art GaAs/AlxGa1-xAs quantum-well infrared photodetectors (QWIPs) could be substantially excelled with about 1-100 μm using κ-([Al,In]xGa1-x)2O3, while at the same time being transparent to visible light and therefore insensitive to photon noise due to its wide band gap, demonstrating the application potential of this material system. Our simulations further show that the QWIPs efficiency critically depends on the QW thickness, making a precise control over the thickness during growth and a reliable thickness determination essential. We demonstrate that pulsed laser deposition yields the needed accuracy, by analyzing a series of (InxGa1-x)2O3 QWs with (AlyGa1-y)2O3 barriers with high-resolution X-ray diffraction, X-ray photoelectron spectroscopy (XPS) depth profiling, and transmission electron microscopy (TEM). While the superlattice fringes of high-resolution X-ray diffraction only yield an average combined thickness of the QWs and the barrier and X-ray spectroscopy depth profiling requires elaborated modeling of the XPS signal to accurately determine the thickness of such QWs, TEM is the method of choice when it comes to the determination of QW thicknesses.
Keywords: X-ray diffraction; X-ray photoelectron spectroscopy depth profiling; heterostructures; interface analysis; pulsed laser deposition; transmission electron microscopy.