Explore the vast range of titles available.

Hybrid infrared (IR) focal plane arrays consist of an array of IR photo-detectors, bump-bonded to a silicon CMOS readout integrated circuit (ROIC) chip. Design and optimisation of ROIC for quantum dot IR detectors is a multidimensional problem. The major design challenge is to select appropriate readout circuit topology to meet the large dynamic range requirement of quantum dot IR photo-detectors within the area dictated by the matched pixel size. Proposed is an efficient design optimisation for ROIC. The optimisation is based on a proposed decision matrix, which leads to a decision merit for ROIC design. Four main specifications, i.e. charge handling capacity, noise, power dissipation and detector bias voltage variations, have been considered. Various architectures have been compared using circuit design, simulation and implementation. The targeted ROIC specifications for a test chip containing a 4 × 4 array are: 5 Mē charge handling capacity, 30 × 30 µm maximum pixel size, snapshot mode of operation, variable integration time, 5 megapixels/s (Mpps) readout rate and readout noise of 600ē at ambient temperature. Also presented is a design with 5 Mē charge handling capacity, which has not been reported for 180 nm CMOS process earlier.

AbstractWe analyze the current state of research in the field of creating unipolar semiconductor barrier structures based on various materials for infrared photodetector arrays, which make it possible to reduce the dark currents and thereby improve the threshold characteristics and ensure operation at high cooling temperatures. The main ways of minimizing a barrier for holes in the valence band are considered by the example of a photosensitive structure based on the n-CMT layer. It is shown that the nBn barrier structures are an alternative for creating photodiode sensing matrices for the mid- and far-infrared photodetector arrays.

The 320 × 256 focal plane arrays based on р + -B–n - N + tetralayer heterostructures with a wide-gap barrier layer have been investigated. The heterostructures with a narrow-gap n -InGaAs absorbing layer were grown by means of metalorganic vapor phase epitaxy on InP substrates. The band discontinuity between the In 0.53 Ga 0.47 As absorbing layer and the In 0.52 Al 0.48 As barrier layer is removed by growing a thin four-component n -AlInGaAs layer with the bandgap gradient variation. Delta-doped layers included into the heterostructures make it possible to lower the barrier in the valence band and eliminate the nonmonotonicity of energy levels. The experimental study of the dark current has been performed. It has been revealed that the average value of the dark current does not exceed 10 fA for the photodiode arrays with a pitch of 30 μm.

Methods for measuring the current-voltage characteristics ( I–V curves) of photodiodes in a 6 × 576 mercury-cadmium-tellurium (MCT) multirow photodetector designed for operation in the longwave part of the infrared (IR) spectral range are analyzed. The I–V curve is plotted using the resultes of measurements of output signals of a large-scale readout integrated circuit (ROIC) hybridized with a row of IR photodiodes. The method of independent current measurement at each point of the I–V curve is compared to the method of additive current measurements. A method of determining optimum working points of photodiodes by plotting and analyzing the dependence of the differential resistance of photodiode on the bias voltage is proposed. Distributions of photodiode currents for a sample of a 6 × 576-element focal plane array (FPA) based on MCT photodiodes with a p -type conductivity substrate having the cutoff wavelength of λ 0.5 = 10.5 μm are considered.

Purpose – The purpose of this paper is to demonstrate a successful fabrication of 2 × 128 linear array of typical infrared (IR) detectors made of p-type tSi/porous Si Schottky barrier. Design/methodology/approach – Using metal-assisted chemical etching (MaCE) as a unique approach, a sample definition of a porous Si nanostructure region for fabricating of any high-density photodetectors array has been formulated. Besides, the uniformity of pixels at different position along the array has been confirmed by optical images and measurements of photocurrent in IR regime at room temperature. Findings – The experimental result illustrates the existence of an open-circuit voltage up to 30 mV at 1.5-μm wavelength for an area of 50 × 50 μm2. Additionally, this behavior is almost the same at different pixels of fabricated array. Research limitations/implications – The uniformity of pixels and definition of nanostructure region are two most important challenges in fabrication of any high-density photodetectors array. Practical implications – MaCE guarantees formation of reproducible, high-fidelity and controllable nanometer-size porous Si with well-defined and sharp edges of the patterned areas. Originality/value – The proposed method offers a low-cost and simple process to fabricate high-density arrays of Schottky detectors which are compatible with the complementary metal-oxide semiconductor process.

The Leti-Lir has studied II-VI compounds for infrared (IR) detection for more than 20 years. The need to reduce the production cost of IR focal plane arrays (FPAs) sparked the development of heteroepitaxy on large-area substrates. Germanium has been chosen as the heterosubstrate for the third generation of IR detectors. First, we report on the progress achieved in HgCdTe growth on 3-in. and 4-in. (211)B CdTe/Ge. Then, we discuss the choice of a new machine for larger size and better homogeneity. Finally, we present the latest results on third-generation IR multicolor and megapixel devices. First-time results regarding a middle wavelength infrared (MWIR) dual-band FPA, with a reduced pitch of 25 µm, and a MWIR 1,280 × 1,024 FPA will be shown. Both detectors are based on molecular beam epitaxy (MBE)-grown HgCdTe on Ge. The results shown validate the choice of Ge as the substrate for third-generation detectors. [PUBLICATION ABSTRACT]