GaSbBi alloys and heterostructures: fabrication and properties

International audienceDilute bismuth (Bi) III-V alloys have recently attracted great attention, due to their properties of band-gap reduction and spin-orbit splitting. The incorporation of Bi into antimonide based III-V semiconductors is very attractive for the development of new optoelectronic devices working in the mid-infrared range (2-5 µm). However, due to its large size, Bi does not readily incorporate into III-V alloys and the epitaxy of III-V dilute bismides is thus very challenging. This book chapter presents the most recent developments in the epitaxy and characterization of GaSbBi alloys and heterostructures

Thermal Imaging with Novel Infrared Focal Plane Arrays and Quantitative Analysis of Thermal Imagery

We have developed a single long-wavelength infrared (LWIR) quantum well infrared photodetector (QWIP) camera for thermography. This camera has been used to measure the temperature profile of patients. A pixel coregistered simultaneously reading mid-wavelength infrared (MWIR)/LWIR dual-band QWIP camera was developed to improve the accuracy of temperature measurements especially with objects with unknown emissivity. Even the dualband measurement can provide inaccurate results due to the fact that emissivity is a function of wavelength. Thus we have been developing a four-band QWIP camera for accurate temperature measurement of remote object

Tailoring the ferroelectric and magnetic properties of Bi5Ti3FeO15 ceramics by doping with Co and Y

The ferroelectric and magnetic properties of four-layered Aurivillius Bi5Ti3FeO15 (BFT) compounds via partial substitution of Bi3+ with Y3+ and Fe3+ with Co2+ (according to formula: Bi5-xYxTi3FeO15, x = 0.1, 0.2, 0.3; Bi5Ti3Fe1-yCoyO15, y = 0.1, 0.3, 0.5) were investigated. Polycrystalline ceramics of Co and Y substituted BFT were prepared by conventional solid-state reaction. Crystal structure and phase purity were confirmed via X-ray diffraction and Rietveld refinement. Raman spectral signatures indicate that Y replaces Bi ions in the pseudo-perovskite layers and Co replaces Fe ions in the octahedral sites. SEM micrographs show a decrease in grain size for both chemically modified samples when compared to plate-like morphology for unmodified BFT with dimensions ranging from 3 to 5 μm in length and a thickness of ∼0.5 μm. The decrease in grain size is more pronounced in Co substituted samples with plate-like grain dimensions of 1 μm in length and 0.2 μm in thickness. Ferroelectric measurements show unsaturated leaky hysteresis loops in both chemically modified samples until the maximal applied electric field. Magnetic measurements confirm the paramagnetic nature of unmodified and Y substituted BFT ceramics while Co substituted BFT ceramics exhibit a typical ferromagnetic M-H loop. The largest remanent magnetization value of 0.084 emu/g at room temperature is recorded for the Co2+ substituted sample with x = 0.3

Multi-Color Megapixel QWIP focal plane arrays for remote sensing

In this paper, we will discuss the performance in terms of quantum efficiency, NEAT, uniformity, operability, and modulation transfer functions of the 1024x1024 pixel arrays and the progress of dualband QWIP focal plane array development work

Towards Dualband Megapixel QWIP Focal Plane Arrays

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 x 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 (NEDT) 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 NEDT 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 addition, we have demonstrated MWIR and LWIR pixel co-registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency, NEDT, uniformity, operability, and modulation transfer functions of the 1024 x 1024 pixel arrays and the progress of dualband QWIP focal plane array development work