ystematic optical study of high-x InxGa1-xAs/InP structures for infrared photodetector applications
Tarih
2022Üst veri
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Optical and structural properties in high-x InxGa1-xAs (x > 0.65) samples with varying indium concentration
grown on InP (100) substrate are reported. By increasing the indium fraction, it was found by the high-resolution
X-ray diffraction (HR-XRD) study that the dislocation density in the InxGa1-xAs epitaxial layer significantly
increased, and the surface quality deteriorated remarkably. Photoreflectance (PR) spectra show the presence of
Franz-Keldysh Oscillations (FKOs) features above the InxGa1-xAs energy bandgap. The strain-induced electric
field is then estimated directly from the FKOs periods. Temperature-dependent photoluminescence (TDPL)
measurements from 10 K to 300 K showed carrier locations (S-shape). This abnormal behavior is due to the
dislocation density associated with fluctuations in the indium concentration. A quasi-stationary rate equation
model for the temperature-dependent luminescence spectra of the localized state material system is proposed to
interpret the band gap emission process quantitatively. Low-temperature (10 K) time-resolved PL measurements
show the increase of lifetime with increasing the indium concentration. Yet, the addition of only 1.7% of indium
concentration results in a strong enhancement of PL lifetime by ~ 80%.
All these results reveal a more precise picture of the localization and recombination mechanisms of photogenerated carriers in the InGaAs layer, which could be the crucial factors in controlling the performance of high
indium content InGaAs SWIR detector.