We report a normal-incident quantum well infrared photodetector (QWIP) strongly coupled with surface plasmon modes. A periodic hole array perforated in gold film was integrated with In0.53Ga0.47As/InP QWIP to convert normal-incident electromagnetic waves into surface plasmon waves, and to excite the intersubband transition of carriers in the quantum wells. The peak responsivity of the photodetector at ∼8 μm was ∼7 A/W at the bias of 0.7 V at 78 K with the peak detectivity as high as ∼7.4×1010 cm Hz1/2/W. The full width at half maximum of the response spectrum was only ∼0.84 μm due to a narrow plasmonic resonance.

http://www.bisol.northwestern.edu/web/papers/ApplPhysLett_96_161107.pdf

Plasmonic enhanced quantum well infrared photodetector with high detectivity

Comparison and competition between MCT and QW structure material for use in IR detectors

Dark current noise measurements were carried out between 10 and 10/sup 4/ Hz at T=80 K on two InGaAs-InP quantum-well infrared photodetectors (QWIPs) designed for 8-/spl mu/m infrared (IR) detection. Using the measured noise data, we have calculated the thermal generation rate, bias-dependant gain, electron trapping probability, and electron diffusion length. The calculated thermal generation rate (/spl sim/7/spl times/10/sup 22/ cm/sup -3//spl middot/s/sup -1/) is similar to AlGaAs-GaAs QWIPs with similar peak wavelengths, but the gain is 50/spl times/ larger, indicating improved transport and carrier lifetime are obtained in the binary InP barriers.

Noise performance of InGaAs-InP quantum-well infrared photodetectors

We report the detailed characteristics of long-wavelength infrared InP-In/sub 0.53/Ga/sub 0.47/As quantum-well infrared photodetectors (QWIPs) and 640/spl times/512 focal plane array (FPA) grown by molecular beam epitaxy. For reliable assessment of the detector performance, characterization was performed on test detectors of the same size and structure with the FPA pixels. Al/sub 0.27/Ga/sub 0.73/As-GaAs QWIPs with similar spectral response (/spl lambda//sub p/=/spl sim/7.8 /spl mu/m) were also fabricated and characterized for comparison. InP-InGaAs QWIPs (20-period) yielded quantum efficiency-gain product as high as 0.46 under -3-V bias with a 77-K peak detectivity above 1/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W. At 70 K, the detector performance is background limited with f/2 aperture up to /spl sim/ 3-V bias where the peak responsivity (2.9 A/W) is an order of magnitude higher than that of the AlGaAs-GaAs QWIP. The results show that impact ionization in similar InP-InGaAs QWIPs does not start until the average electric-field reaches /spl sim/25 kV/cm, and the detectivity remains high under moderately large bias, which yields high responsivity due to large photoconductive gain. The InP-InGaAs QWIP FPA offers reasonably low noise equivalent temperature difference (NETD) even with very short integration times (/spl tau/).70 K NETD values of the FPA with f/1.5 optics are 36 and 64 mK under bias voltages of -0.5 V (/spl tau/=11 ms) and -2 V (/spl tau/=650 /spl mu/s), respectively. The results clearly show the potential of InP-InGaAs QWIPs for thermal imaging applications requiring high responsivity and short integration times.

High responsivity InP-InGaAs quantum-well infrared photodetectors: characteristics and focal plane array performance

There have been various studies showing that InP-InGaAs quantum-well infrared photodetectors (QWIPs) are potential alternatives to AlGaAs-GaAs QWIPs in the long wavelength infrared (LWIR) band, especially for applications requiring high responsivity. Being on InP substrate, this material system also offers lattice matched mid-wavelength infrared (MWIR)/LWIR dual band QWIP stack when it is used with the AlInAs-InGaAs system. It is desirable to extend the cut-off wavelength of InP based LWIR QWIPs to , which can be accomplished by replacing the QW material with InGaAsP. In this paper, we report the first InP-InGaAsP QWIP focal plane array (FPA). The 640 512 FPA displayed remarkably low noise equivalent temperature difference (NETD) with very short integration times (46 mK at 66 K with and f/1.5 optics). The results show that these QWIPs can be operated with high responsivity (1 A/W) while offering bias adjustable gain in a wide range where the detectivity is almost constant at a reasonably high level.

Demonstration and Performance Assessment of Large Format InP–InGaAsP Quantum-Well Infrared Photodetector Focal Plane Array

In0.53Ga0.47As/InP infrared detectors with peak absorption at a wavelength of 8.5 micrometers have been fabricated and tested. It is shown that very high current responsivities and high gain are obtained. It is found that gain increases drastically when approaching detector voltages close to -8.5 V, which is explained by carrier impact excitation of electrons from the QW ground state to the excited extended state. The detectivity D* is about 1.2(DOT)1010 cm Hz1/2 W-1 at 80 K for a 45 degree(s) polished edge detector assuming unpolarized radiation. Grating coupling is studied by etching crossed gratings into the upper part of the mesas. The increase in responsivity as compared to a polished edge detector is by a factor of 2.5 to 3, irrespective to mesa sizes 500 X 500 or 150 X 150 micrometers 2. This gives a corresponding detectivity of (3 - 3.5)(DOT)1010 cm Hz1/2 W-1 at 80 K for unpolarized radiation.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Klaus P. Streubel

Papers

Long-wavelength quantum-well infrared detectors based on intersubband transitions in InGaAs/InP quantum wells