Temperature Dependent Intersubband Dynamics in N — Modulation Doped Quantum Well Structures

Seilmeier, A.; Plödereder, U.; Baier, Johannes; Weimann, G.

doi:10.1007/978-94-011-1144-7_36

Cited by 6 publications

(2 citation statements)

References 17 publications

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“…The use of a solid film reduces the 300 K intersubband relaxation time from that which is otherwise expected for the same sample in solution at room temperature, as shown in Figure b. CQW intersubband relaxation becomes faster at higher sample temperatures (Figure c), consistent with previous spectroscopic results − and known thermal constraints of QCLs and QWIPs . As samples are cooled, the ambient population of phonons, which is also reflected in the similar trend of the full-width at half-maximum of the intersubband absorption in Figure c is reduced and relaxation slows to a rate limited by phonon emission .…”

Section: Results and Discussionsupporting

confidence: 85%

Intersubband Relaxation in CdSe Colloidal Quantum Wells

Diroll

Schaller

2020

ACS Nano

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The dynamics of intersubband relaxation are critical to quantum well technologies such as quantum cascade lasers and quantum well infrared photodetectors. Here, intersubband relaxation in CdSe colloidal quantum wells, or nanoplatelets, is studied via pump–push–probe transient spectroscopy. An initial interband pump pulse is followed by a secondary infrared push excitation, resonant with intersubband absorption, which promotes electrons from the first conduction band of the quantum well to the second conduction band. A probe pulse monitors subsequent electron cooling to the band edge of the quantum well. Using this technique, intersubband relaxation is studied as a function of critical variables such as colloidal quantum well size and thickness, surface ligand chemistry, temperature, and excitation pulse intensity. Larger quantum well sizes, judicious selection of surface ligand chemistry (e.g., thiolates), low temperatures, and elevated push pulse fluences slow intersubband relaxation. However, compared to resonant intraband relaxation in colloidal quantum dots (up to hundreds of picoseconds), intersubband relaxation in colloidal quantum wells is rapid (<1 ps) under all examined conditions. These experiments indicate that rapid relaxation is driven by both LO phonon and surface scattering. The short time scale of relaxation observed in these materials may hinder intersubband technologies such as mid-infrared detectors, although such rapid relaxation may prove valuable in optical switching.

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Section: Results and Discussionsupporting

confidence: 85%

Intersubband Relaxation in CdSe Colloidal Quantum Wells

Diroll

Schaller

2020

ACS Nano

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“…The heterostructure, created by the adjustable bandgap of AlGaAs, enforces quantum confinement, limiting electron and hole movement in the vertical direction but allowing lateral motion. This results in discrete energy levels, so-called subbands, in the quantum well [36]. A distinctive feature of the on-chip THz circular-polarization detector is the composite structure of the chiral antenna and the III-V semiconductor layers (Figure 1a).…”

Section: Device Structurementioning

confidence: 99%

Enhanced THz Circular-Polarization Detection in Miniaturized Chips with Chiral Antennas

Li,

Zhou,

Deng

et al. 2024

Photonics

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Recent advancements in terahertz (THz) wave technology have highlighted the criticality of circular-polarization detection, fostering the development of more compact, efficient on-chip THz circular-polarization detectors. In response to this technological imperative, we presented a chiral-antenna-integrated GaAs/AlGaAs quantum well (QW) THz detector. The chiral antenna selectively couples the incident light of a specific circular-polarization state into a surface-plasmon polariton wave that enhances the absorptance of the QWs by a factor of 12 relative to a standard 45° faceted device, and reflects a significant amount of the incident light of the orthogonal circular-polarization state. The circular-polarization selectivity is further enhanced by the QWs with a strong intrinsic anisotropy, resulting in a circular-polarization extinction ratio (CPER) as high as 26 at 6.52 THz. In addition, the operation band of the device can be adjusted by tuning the structural parameters of the chiral structure. Moreover, the device preserves a high performance for oblique incidence within a range of ±5°, and the device architecture is compatible with a focal plane array. This report communicates a promising approach for the development of miniaturized on-chip THz circular-polarization detectors.

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Spectral Dynamics of The Intersubband Absorption in Quantum Well Structures After Ultrafast IR Excitation

Kaiser

Seilmeier

1998

Intersubband Transitions in Quantum Wells: Physics and Devices

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Temperature Dependent Intersubband Dynamics in N — Modulation Doped Quantum Well Structures

Cited by 6 publications

References 17 publications

Intersubband Relaxation in CdSe Colloidal Quantum Wells

Intersubband Relaxation in CdSe Colloidal Quantum Wells

Enhanced THz Circular-Polarization Detection in Miniaturized Chips with Chiral Antennas

Spectral Dynamics of The Intersubband Absorption in Quantum Well Structures After Ultrafast IR Excitation

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