Temperature dependence of intersubband transitions in InAs/AlSb quantum wells

Larrabee, D. C.; Khodaparast, Giti A.; Kono, Junichiro; Ueda, K.; Nakajima, Yoji; Nakai, M.; Sasa, Shigehiko; Inoue, M.; Kolokolov, K. I.; Li, J.; Ning, Cun‐Zheng

doi:10.1063/1.1626264

“…Although the 2.6 meV larger shift in S3 reflects the stronger non-parabolicity and mixing with lh/so states of the hh2 state, the similar peak shift values of the two samples suggests the importance of the temperature dependence of E xc as in the case of the intersubband transitions in n-GaAs QWs 21 and n-InAs QWs. 22 Similarly to these QWs, we found that 9 peak shift due to the temperature dependence of the band parameters is one order of magnitude too small and cannot account for the experiment in p-SiGe QWs.…”

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confidence: 91%

Intra-valence-band mixing in strain-compensatedSiGequantum wells

Tsujino

¹

,

Borak

²

,

Falub

³

et al. 2005

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We explore the midinfrared absorption of strain-compensated p-Si 0.2 Ge 0.8 /Si quantum wells for various well thicknesses and temperatures. Owing to the large band offset due to the large bi-axial strain contrast between the wells and barriers, the intersubband transitions energies from the ground state to the excited heavy hole (hh), light hole (lh) and split-off hole (so) states are resolved to ~0.5 eV. When hh2 is withiñ 30 meV of lh1 or so1 a partial transfer of the hh1-hh2 oscillator strength to the hh1-lh1 or hh1-so1 transitions is observed, which is otherwise forbidden for light polarized perpendicular to the plane of the wells. This is a clear sign of mixing between the hh and lh or so-states. A large temperature induced broadening of hh2 peak is observed for narrow wells indicating a non-parabolic dispersion of the hh2 states due to the mixing with the lh/so continuum. We found that the 6-band k•p theory gives a quantitative account of the observations. A possible role of many-body effects in the temperatureinduced negative peak shift is discussed. 73.21.Fg, 78.30.Hv, 78.67.De

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“…An intersubband device should operate at and above 300 K, often with the condition of a negligible change in transition energy. Temperature dependence of the transition energy, up to room temperature, has been reported for intersubband absorption in InAs/AlSb multiple quantum well (MQW) structures [7] and for interband photoluminescence in nitride-based AlN/GaN MQW structures.…”

mentioning

confidence: 99%

“…An intersubband device should operate at and above 300 K, often with the condition of a negligible change in transition energy. Temperature dependence of the transition energy, up to room temperature, has been reported for intersubband absorption in InAs/AlSb multiple quantum well (MQW) structures [7] and for interband photoluminescence in nitride-based AlN/GaN MQW structures. [8] The huge piezoelectric fields introduce an additional temperature-dependent effect in the nitride MQW structures, because the different thermal expansions of AlN and GaN induce a temperature dependent strain in the structures.…”

mentioning

confidence: 99%

“…An intersubband device should operate at and above 300 K, often with the condition of a negligible change in transition energy. Temperature dependence of the transition energy, up to room temperature, has been reported for intersubband absorption in InAs/AlSb multiple quantum well (MQW) structures [7] and for interband photoluminescence in nitride-based AlN/GaN MQW structures.[8] The huge piezoelectric fields introduce an additional temperature-dependent effect in the nitride MQW structures, because the different thermal expansions of AlN and GaN induce a temperature dependent strain in the structures.In this letter, we demonstrate that the peak position of intersubband transitions red shifts only ∼ 6 meV as the temperature of the sample is increased from 25 • to 400 • C. This aspect of thermal robustness could be vital for the operation of nitride-based QCLs since their ultrafast LO-scattering rates and high intersubband energy would cause them to heat significantly. The temperature effects are studied for MQW structures both experimentally by measuring the absorption at different temperatures, and theoretically by a self-consistent solution to the Schrödinger-Poisson equations for the conductionband electrons.…”

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confidence: 99%

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Temperature stability of intersubband transitions in AlN/GaN quantum wells

Berland

¹

,

Stattin

²

,

Farivar

³

et al. 2010

Applied Physics Letters

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Temperature dependence of intersubband transitions in AlN/GaN multiple quantum wells grown with molecular beam epitaxy is investigated both by absorption studies at different temperatures and modeling of conduction-band electrons. For the absorption study, the sample is heated in increments up to 400 • C. The self-consistent Schrödinger-Poisson modeling includes temperature effects of the band-gap and the influence of thermal expansion on the piezoelectric field. We find that the intersubband absorption energy decreases only by ∼ 6 meV at 400 • C relative to its room temperature value.Intersubband transitions in nitride-based semiconductor heterostructures hold great promise for optoelectronic devices. The high band-offset between gallium nitride (GaN) and aluminum nitride (AlN) enables intersubband transitions in the near-infrared regime (λ = 1-4 µm). Thus, intersubband devices such as modulators, detectors, and quantum cascade lasers (QCLs) have the potential to operate at wavelengths useful for fiberoptic communication. QCLs also have the potential to be used when measuring characteristic absorption of small molecules. There are several studies of intersubband absorption in AlN/GaN heterostructures.[1-6] These typically show a peak at 500 to 900 meV with full width half maximum (FWHM) in the range of 60 to 200 meV. An intersubband device should operate at and above 300 K, often with the condition of a negligible change in transition energy. Temperature dependence of the transition energy, up to room temperature, has been reported for intersubband absorption in InAs/AlSb multiple quantum well (MQW) structures [7] and for interband photoluminescence in nitride-based AlN/GaN MQW structures.[8] The huge piezoelectric fields introduce an additional temperature-dependent effect in the nitride MQW structures, because the different thermal expansions of AlN and GaN induce a temperature dependent strain in the structures.In this letter, we demonstrate that the peak position of intersubband transitions red shifts only ∼ 6 meV as the temperature of the sample is increased from 25 • to 400 • C. This aspect of thermal robustness could be vital for the operation of nitride-based QCLs since their ultrafast LO-scattering rates and high intersubband energy would cause them to heat significantly. The temperature effects are studied for MQW structures both experimentally by measuring the absorption at different temperatures, and theoretically by a self-consistent solution to the Schrödinger-Poisson equations for the conductionband electrons. The nitride-semiconductor heterostructures are characterized by huge internal electric fields, which arise from the exceptionally large spontaneous and piezoelectric fields. A proper account of these fields are crucial for an accurate description and characterization of the quantum well states, and they require that the complete structure is considered in the design of heterostructures.The set of MQW structures (A -C) are grown in a Varian Gen II modular molecular beam epitaxy (MBE) system....

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“…This arises from how both the band-edges of the barriers and QWs are changing at approximately the same rate in energy and produce a negligible change in terms of the QW depth for both the HH and LH bands. 19,20 It is also evident from the spectra that there is a longer wavelength absorption peak appearing with the decreasing temperature at $10.2 lm wavelength. Most likely, the Fermi level enters the HH1 subband at low temperature, activating the HH1-HH2 transition.…”

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confidence: 86%