Sir B. Rafol

High-temperature operation of InAs-GaAs quantum-dot infrared photodetectors with large responsivity and detectivity

We have optimized the growth of multiple (40-70) layers of self-organized InAs quantum dots separated by GaAs barrier layers in order to enhance the absorption of quantum-dot infrared photodetectors (QDIPs). In devices with 70 quantum-dot layers, at relatively large operating biases (/spl les/-1.0 V), the dark current density is as low as 10/sup -5/ A/cm/sup 2/ and the peak responsivity ranges from /spl sim/0.1 to 0.3 A/W for temperatures T=150 K-175 K. The peak detectivity corresponding to these low dark currents and high responsivities varies in the range 6/spl times/10/sup 9//spl les/D/sup */(cm/spl middot/Hz/sup 1/2//W)/spl les/10/sup 11/ for temperatures 100/spl les/T(K)/spl les/200. These performance characteristics represent the state-of-the-art for QDIPs and indicate that this device heterostructure is appropriate for incorporation into focal plane arrays.

1024 × 1024 pixel mid-wavelength and long-wavelength infrared QWIP focal plane arrays for imaging applications

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 × 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEΔT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEΔT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In this paper, we will discuss the performance in terms of quantum efficiency, NEΔT, uniformity, operability and modulation transfer functions.

Submonolayer quantum dot infrared photodetector

We describe the concept of the submonolayer quantum dot infrared photodetector (SML QDIP) and report experimental device results on long-wavelength infrared detection. An SML QDIP structure was fabricated into megapixel focal plane arrays, which produced clear infrared images up to 80 K. Detectors in the focal plane showed a responsivity peak at 7.8 μm and noise equivalent temperature difference of 33 mK at 70 K.We describe the concept of the submonolayer quantum dot infrared photodetector (SML QDIP) and report experimental device results on long-wavelength infrared detection. An SML QDIP structure was fabricated into megapixel focal plane arrays, which produced clear infrared images up to 80 K. Detectors in the focal plane showed a responsivity peak at 7.8 μm and noise equivalent temperature difference of 33 mK at 70 K.

640 /spl times/ 512 pixel long-wavelength infrared narrowband, multiband, and broadband QWIP focal plane arrays

A 640 /spl times/ 512 pixel, long-wavelength cutoff, narrowband (/spl Delta//spl lambda///spl lambda//spl sim/10%) quantum-well infrared photodetector (QWIP) focal plane array (FPA), a four-band QWIP FPA in the 4-15 /spl mu/m spectral region, and a broadband (/spl Delta//spl lambda///spl lambda/ /spl sim/ 42%) QWIP FPA having a 15.4 /spl mu/m cutoff have been demonstrated. In this paper, we discuss the electrical and optical characterization of these FPAs, and their performance. In addition, we discuss the development of a very sensitive (NEDT /spl sim/ 10.6 mK) 640 /spl times/ 512 pixel thermal imaging camera having a 9 /spl mu/m cutoff.

Demonstration of a 1024

We describe the demonstration of a 1024 × 1024 pixel long-wavelength infrared focal plane array based on an InAs-GaSb superlattice absorber surrounded by an electron-blocking and a hole-blocking unipolar barrier. An 11.5-μm cutoff focal plane without antireflection coating based on this complementary barrier infrared detector design has yielded noise equivalent differential temperature of 53 mK at operating temperature of 80 K, with 300 K background and f/2 cold-stop.

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Abstract One of the simplest device realizations of the classic particle-in-the-box problem of basic quantum mechanics is the quantum well infrared photodetector (QWIP). In this paper, we discuss the effect of focal plane array nonuniformity on the performance, optimization of the detector design, material growth and processing that has culminated in realization of large format long-wavelength QWIP cameras, holding forth great promise for many applications in 6–18 μm wavelength range in science, medicine, defense and industry. In addition, we present the recent developments in long-wavelength/very long-wavelength dualband QWIP imaging camera for various applications.

1024 Pixel InAs–GaSb Superlattice Focal Plane Array

The spectral response of quantum-well infrared photodetectors (QWIPs) based on the III-V material system are tailorable to narrow or broad bandwidths within mid- and long-wavelength infrared bands. Typical broad-band QWIPs show considerable spectral shape change with bias voltage, particularly near the cut-off wavelength region. Two alternatives to the typical broadband QWIP design have been demonstrated. These designs consist of two multiquantum-well (QW) stacks or alternatively placed QWs and produce nearly fixed spectrums within the operating bias voltages. Flexibility in many design parameters of these detectors allows for tuning and tailoring the spectral shape according to application requirements, specifically for spectral imaging instruments.

Quantum well infrared photodetector research and development at Jet Propulsion Laboratory

Long-wavelength complementary barrier infrared detector (CBIRD) based on III-V material is hybridized to recently designed and fabricated 320 × 256 pixel format two-color read-out integrated circuit. The n-type CBIRD is characterized in terms of performance and thermal stability. This paper reports on the measured dark current density, noise equivalent difference temperature, quantum efficiency, responsivity, minimum resolvable difference temperature, and modulation transfer function.

Tuning and tailoring of broadband quantum-well infrared photodetector responsivity spectrum

In this letter, we demonstrate the next generation of N+-p complementary barrier infrared detectors (nCBIRD) with 9.9 μm cutoff wavelength that have near zero bias operation and exhibit dark current density of 6 × 10-6 A/cm2 at 77 K. These nCBIRDs have been recently utilized in the 320 × 256 focal plane array that exhibited a noise equivalent differential temperature of 18.6 mK at an operating temperature of 77 K, with a 300 K background and f/2 cold-stop. We compare single pixel photodiode characteristics with the performance of FPAs that were fabricated together on the same wafer. This letter identifies the physical processes affecting the performance of long wave infrared photodetectors based on CBIRD design.

Performance of a 1/4 VGA Format Long-Wavelength Infrared Antimonides-Based Superlattice Focal Plane Array

Abstract We present an overview of III-V semiconductor-based infrared detector and focal plane array development at the NASA Jet Propulsion Laboratory in recent years. Topics discussed include: (1) the development of long-wavelength quantum well infrared photodetector for imaging spectrometer applications, (2) the concept and realization of the submonolayer quantum dot infrared photodetector (SML-QDIP) as an alternative to the standard QDIP-based on Stranski-Krastanov (SK) quantum dots, (3) the mid-wavelength infrared quantum dot barrier infrared detector with extended cutoff wavelength, and (4) high-performance type-II superlattice long-wavelength infrared detectors based on the complementary barrier infrared detector architecture.