Progress in resonator quantum well infrared photodetector (R-QWIP) focal plane arrays

In this work, the performance of a 640 X 512 long-wavelength resonant quantum well infrared photodetector (R-QWIP) focal plane array (FPA) was evaluated as a function of operating temperature, bias, and photon flux using an F/2.2 optic. From these FPA measurements an assessment of the dark current, noise, conversion efficiency and noise-equivalent temperature difference is provided herein. Histogram results are used to support a statistical interpretation of operability and non-uniformity across the R-QWIP FPA. In addition, single pixel devices fabricated from the same wafer lot enabled supplemental noise gain and spectral response measurements. The spectral response of this R-QWIP structure was confirmed to peak around 8.3 microns with a spectral bandwidth or approximately 1 micron (full-width half maximum) and the noise gain measurements were used to provide an estimation of the expected external quantum efficiency (conversion efficiency = quantum efficiency ⁄ gain)

Infrared Reflectance Analysis of Epitaxial n-Type Doped GaN Layers Grown on Sapphire

Abstract Infrared (IR) reflectance spectroscopy is applied to study Si-doped multilayer n+/n0/n+-GaN structure grown on GaN buffer with GaN-template/sapphire substrate. Analysis of the investigated structure by photo-etching, SEM, and SIMS methods showed the existence of the additional layer with the drastic difference in Si and O doping levels and located between the epitaxial GaN buffer and template. Simulation of the experimental reflectivity spectra was performed in a wide frequency range. It is shown that the modeling of IR reflectance spectrum using 2 × 2 transfer matrix method and including into analysis the additional layer make it possible to obtain the best fitting of the experimental spectrum, which follows in the evaluation of GaN layer thicknesses which are in good agreement with the SEM and SIMS data. Spectral dependence of plasmon-LO-phonon coupled modes for each GaN layer is obtained from the spectral dependence of dielectric of Si doping impurity, which is attributed to compensation effects by the acceptor states