Molecular beam epitaxy growth of inp/ingaas structures for short wavelength infrared photodetectors

Temel, Oğuzhan
Indium Gallium Arsenide (In0.53Ga0.47As) is a suitable compound semiconductor for photodetector applications in the Short Wavelength Infrared (SWIR) band with its ~1.7 µm cut-off wavelength. In this work, lattice-matched InxGa1-xAs compounds (x~0.53) were grown on InP (001) substrates by the molecular beam epitaxy (MBE) method. Unintentional doping level as low as 1.96E15 cm-3 was obtained in the In0.53Ga0.47As epilayers. The X-ray diffraction full width at half maximum values were as low as 45 arc-sec displaying the high crystal quality of the epilayers. The device structures with the epilayers of n+InP/In0.53Ga0.47As/p+InP and n+InP/In0.53Ga0.47As/p+In0.52Al0.48As were grown, and their structural characterization was conducted. Test detectors with large area mesas (200x200 and 300x300 µm2) were fabricated with a non-optimized fabrication process for electrical and optical characterization. The aim of the characterization of the test detectors was to determine the material’s preliminary device performance. The peak responsivity of the test detectors was ~1 A/W at room temperature under 100 mV reverse bias. The corresponding quantum efficiency near the cut off wavelength is ~75%. The dark current of the test detectors under small reverse bias was dominated by the generation-recombination mechanism at room temperature. The dark current density of the test detectors with ~1.7 µm cut-off wavelength at 298 K (100 mV reverse bias) was 2.5 µA/cm2 with a fabrication process which has not been optimized yet.