Publications (3)3.22 Total impact
Article: Demonstration of Bias-Controlled Algorithmic Tuning of Quantum Dots in a Well (DWELL) MidIR Detectors[show abstract] [hide abstract]
ABSTRACT: The quantum-confined Stark effect in intersublevel transitions present in quantum-dots-in-a-well (DWELL) detectors gives rise to a midIR spectral response that is dependent upon the detector's operational bias. The spectral responses resulting from different biases exhibit spectral shifts, albeit with significant spectral overlap. A postprocessing algorithm was developed by Sakoglu that exploited this bias-dependent spectral diversity to predict the continuous and arbitrary tunability of the DWELL detector within certain limits. This paper focuses on the experimental demonstration of the DWELL-based spectral tuning algorithm. It is shown experimentally that it is possible to reconstruct the spectral content of a target electronically without using any dispersive optical elements for tuning, thereby demonstrating a DWELL-based algorithmic spectrometer. The effects of dark current, detector temperature, and bias selection on the tuning capability are also investigated experimentally.IEEE Journal of Quantum Electronics 07/2009; · 1.88 Impact Factor
Article: Resonant cavity enhanced InAs/In0.15Ga0.85As dots-in-a-well quantum dot infrared photodetector[show abstract] [hide abstract]
ABSTRACT: The authors demonstrate the design, growth, fabrication, and characterization of resonant cavity enhanced In As / In <sub>0.15</sub> Ga <sub>0.85</sub> As dots-in-a-well (RC-DWELL) quantum dot infrared photodetector (QDIP) and compare it with a standard DWELL detector. They measured peak photoresponse at the resonant wavelength of 9.5 μ m for the RC-DWELL photodetector. The peak responsivity was measured to be 0.76 A / W at 1.4 V and the peak detectivity was 1.4×10<sup>10</sup> cm Hz <sup>1/2</sup>/ W at 0.5 V at a temperature of 77 K . The photocurrent density increased in comparison with the standard DWELL structure with the same active region by a factor of 6 at V<sub>b</sub>=2.1 V and 80 K . A factor of 6 increase in responsivity and factor of 3 increase in detectivity at 1.2 V and 77 K were also observed in the resonant cavity enhanced DWELL sample. The quantum efficiencies for the RC-DWELL sample were calculated to be ∼10% at 9.5 μ m and 1.25% at 10 μ m for the standard DWELL sample. They conclude that the RC-DWELL is a promising improvement for QDIP-based infrared detection applications.Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 08/2007; · 1.34 Impact Factor
[show abstract] [hide abstract]
ABSTRACT: The authors report the design, growth, fabrication, and characterization of a low-strain quantum dots-in-a-well DWELL infrared photodetector. This novel DWELL design minimizes the inclusion of the lattice-mismatched indium-containing compounds while maximizing the absorption cross section by enabling larger active region volume. The improved structure uses an In 0.15 Ga 0.85 As/ GaAs double well structure with Al 0.10 Ga 0.90 As as the barrier. Each layer in the active region was optimized for device performance. Detector structures grown using molecular beam epitaxy were processed and characterized. This new design offers high responsivity of 3.9 A / W at a bias of 2.2 V and a detectivity of 3 10 9 Jones at a bias of 2.2 V for a wavelength of 8.9 m. These detectors offer significant improvement in the responsivity while retaining the long wave infrared spectral properties of the InAs/ In 0.15 Ga 0.85 As/ GaAs DWELL. These detectors if coupled with improved noise characteristics could enable higher temperature operation of DWELL detectors, thus reducing the dependence on cooling equipment.