The wide band gap semiconductor κ-Ga2O3and 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)2O3QWs with (AlyGa1-y)2O3barriers 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.