Optimization of various growth parameters for Type-II GaSb (10MLs)/InAs(10MLs) nanoscale superlattices (SL) and
GaSb layers, grown by solid molecular beam epitaxy, has been undertaken. We present optical and structural
characterization for these heterostructures, using high resolution X-ray diffraction (HRXRD), photoluminescence (PL)
and atomic force microscopy (AFM). Optimized parameters were then used for growth of InAs/GaSb SLs photovoltaic
detectors (λcut-off ~5 μm) operating at room temperature. By controlling the nature of interfaces, the in-plane mismatch
between GaSb-buffer layer and SLs can be reduced enabling the growth of active regions up to 3μm. Normal incidence
single pixel photodiodes were fabricated using standard lithography with apertures ranging from 25-300 μm in diameter.
The spectral response from the SLs detector was observed at room temperature. This suggests the potential of the SLs
technology for realizing high operating temperature (HOT) sensors. Responsivity measurements were also undertaken
using a calibrated black body source, 400Hz optical chopper, SR 770 FFT Network signal analyzer and Keithley 428
preamplifier. We obtained current responsivity equal 2.16 A/W at V = -0.3V(300K). The Johnson noise limited D* at
300K was estimated to be 4.6x109 cm·Hz1/2/W at V = -0.3V
In this paper we report the use of a photonic crystal resonant cavity to increase the quantum efficiency, detectivity (D*) and the background limited infrared photodetector (BLIP) temperature of a quantum dot detector. The photonic crystal is incorporated in InAs/InGaAs/GaAs dots-in-well (DWELL) detector using Electron beam lithography. From calibrated blackbody measurements, the conversion efficiency of the detector with the photonic crystal (DWELL-PC) is found to be 58.5% at -2.5 V while the control DWELL detectors have quantum efficiency of 7.6% at the same bias. We observed no significant reduction in the dark current of the photonic crystal devices compared to the normal structure. The generation-recombination limited D* at 77K with a 300K F1.7 background, is estimated to be 6 x 1010 cmHz1/2/W at -3V bias for the DWELL-PC which is a factor of 20 higher than that of the control sample. We also observed a 20% increase in the BLIP temperature for the DWELL-PCs.