HgCdTe Mid- and Long-Wave Barrier Infrared Detectors for Higher Operating Temperature Condition

In the last decade, a new architecture design such as nBn device or unipolar barrier photodiode has been proposed to achieve high operating temperature condition. This idea has also been implemented into HgCdTe ternary material system. In this chapter, we present the status of HgCdTe barrier detectors grown by metalorganic chemical vapor deposition with emphasis on numerical simulations of their properties. The device concept of a specific barrier bandgap architecture integrated with Auger suppression is a proper solution for high operating temperature infrared detectors. The device performance is comparable with state-of-the-art HgCdTe photodiodes

HgCdTe energy gap determination from photoluminescence and spectral response measurements

The temperature dependence of photoluminescence spectra has been studied for the HgCdTe epilayer. At low temperatures, the signal has plenty of band-tail states and shallow/deep defects which makes it difficult to evaluate the material bandgap. In most of the published reports, the photoluminescence spectrum containing multiple peaks is analyzed using a Gaussian fit to a particular peak. However, the determination of the peak position deviates from the energy gap value. Consequently, it may seem that a blue shift with increasing temperature becomes apparent. In our approach, the main peak was fitted with the expression proportional to the product of the joint density of states and the Boltzmann distribution function. The energy gap determined on this basis coincides in the entire temperature range with the theoretical Hansen dependence for the assumed Cd molar composition of the active layer. In addition, the result coincides well with the bandgap energy determined on the basis of the cut-off wavelength at which the detector response drops to 50% of the peak value

Monte Carlo simulation as a demand forecasting tool

PURPOSE: This article aims to evaluate the effectiveness of Monte Carlo simulation as a tool for demand forecasting.DESIGN/METHODOLOGY/APPROACH: The study analyzes historical data on product sales, fits a theoretical distribution, and then applies Monte Carlo simulation to forecast demand for the next 15 days.FINDINGS: The result of the research shows that Monte Carlo simulation can outperform more straightforward methods such as averaging, particularly in the presence of uncertainty or randomness.PRACTICAL IMPLICATIONS: The study demonstrates how Monte Carlo simulation can improve demand forecasting accuracy, which is crucial for optimizing various business operations.ORIGINALITY/VALUE: This study's novelty lies in demonstrating the practical application of Monte Carlo simulation for demand forecasting and comparing its performance against traditional methods.peer-reviewe

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Low-temperature growth of InAs/GaSb superlattices on miscut GaAs substrates for mid-wave infrared detectors

Short-period 10 monolayers InAs/10ML GaSb type-II superlattices have been deposited on a highly lattice-mismatched GaAs (001), 2° offcut towards substrates by molecular beam epitaxy. This superlattice was designed for detection in the mid-wave infrared spectral region (cut-off wavelength, λcut-off = 5.4 μm at 300 K). The growth was performed at relatively low temperatures. The InAs/GaSb superlattices were grown on a GaSb buffer layer by an interfacial misfit array in order to relieve the strain due to the ~7.6% lattice-mismatch between the GaAs substrate and type-II superlattices. The X-ray characterisation reveals a good crystalline quality exhibiting full width at half maximum ~100 arcsec of the zero-order peak. Besides, the grown samples have been found to exhibit a change in the conductivity