Carrier Recombination, Long‐Wavelength Photoluminescence, and Stimulated Emission in HgCdTe Quantum Well Heterostructures

Abstract

Interband photoluminescence (PL) and stimulation emission (SE) from HgTe/ HgCdTe quantum well (QW) heterostructures are studied in 5-20 mm wavelength range in regard to long-wavelength lasing applications. The authors obtain carrier lifetimes using time-resolved photoconductivity measurements and show that the dominating mechanism of carrier recombination changes from the radiative process to the non-radiative one as the bandgap is decreased, limiting the "operating" temperature for SE. The authors suggest that decreasing the QW width should reverse the balance in carrier recombination in favor of radiative processes and demonstrate 75 K improvement in the "operating" temperature in structure with narrower QW.of the band structure of narrow-gap HgTe/ HgCdTe heterostructures on carrier recombination mechanisms. [4] Recently, it was shown that HgCdTe-based QW can provide stimulated emission in the very longwavelength IR, [5] suggesting that such structures can be interesting for longwavelength emitters.At present moment, the best-performing semiconductor sources for far IR range are quantum cascade lasers (QCLs). They demonstrate ultimate figures of merit almost in the entire IR range. [6] The only "blind spot" of QCLs caused by the strong lattice absorption in traditional production materials (GaAs and InP) lies at wavelengths between 20 and 60 μm. InAs-based and Al-free QCLs are tackling this wavelength range from the mid-IR side, [7] while GaN QCLs have been proposed for frequencies above 5 THz. [8] However, interband lasers are also of interest since they are less demanding from the technological viewpoint and allow wavelength tuning with temperature. The cornerstone of effective light emitter, especially in far infrared range (FIR) range, is to suppress the non-radiative recombination, in

Fundamental Limits to Far-Infrared Lasing in Auger-Suppressed HgCdTe Quantum Wells

“…This occurs primarily due to low optical phonon energy 34 phonon recombination is possible. Radiative recombination due to spontaneous photon emission dominates carrier kinetics in photoexcited mid-infrared wells at cryogenic temperatures, 47 but becomes irrelevant in far-infrared region or at higher temperatures. Note that it does not mean the infeasibility of far-infrared HgCdTe lasers, because it is stimulated emission which drives laser operation, whose rate can be arbitrarily higher than the spontaneous emission rate.…”

Optical Studies and Transmission Electron Microscopy of HgCdTe Quantum Well Heterostructures for Very Long Wavelength Lasers

“…The sample was mounted inside a closed-cycle cryostat optically connected to the spectrometer. Mainly, a CO 2 laser (with operating wavelength of 10.6 μm and pulse duration of ~100 ns) was used for pumping [ 26 ]. The parametric oscillator “Solar OPO” was exploited for several structures, when 2–2.3 μm pumping wavelength was appropriate.…”

Влияние внутренних оптических потерь на генерацию стимулированного излучения в среднем ИК диапазоне в волноводных гетероструктурах с квантовыми ямами HgCdTe/CdHgTe

“…Альтернативой ККЛ в данном диапазоне могут служить межзонные полупроводниковые лазеры с квантовыми ямами (КЯ) HgCdTe/CdHgTe. В подобных длинноволновых лазерах безызлучательная оже-рекомбинация играет важную роль, так как при продвижении в дальний ИК диапазон скорость оже-рекомбинации в них многократно возрастает за счет уменьшения ее пороговой энергии [3], и оже-рекомбинация может являться основным механизмом межзонной рекомбинации [4,5]. Фактором, эффективно повышающим пороговую энергию оже-рекомбинации, является [квази]симметричность законов дисперсии носителей.…”