Measurements of the Electric Field of Zero-Point Optical Phonons in GaAs Quantum Wells Support the Urbach Rule for Zero-Temperature Lifetime Broadening

Bhattacharya R, Mondal R, Khatua P, Rudra A, Kapon E, Malzer S, Döhler G, Pal B, Bansal B (2015)


Publication Status: Published

Publication Type: Journal article, Letter

Publication year: 2015

Journal

Publisher: American Physical Society

Book Volume: 114

DOI: 10.1103/PhysRevLett.114.047402

Abstract

We study a specific type of lifetime broadening resulting in the well-known exponential "Urbach tail" density of states within the energy gap of an insulator. After establishing the frequency and temperature dependence of the Urbach edge in GaAs quantum wells, we show that the broadening due to the zero-point optical phonons is the fundamental limit to the Urbach slope in high-quality samples. In rough analogy with Welton's heuristic interpretation of the Lamb shift, the zero-temperature contribution to the Urbach slope can be thought of as arising from the electric field of the zero-point longitudinal-optical phonons. The value of this electric field is experimentally measured to be 3 kV cm(-1), in excellent agreement with the theoretical estimate.

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How to cite

APA:

Bhattacharya, R., Mondal, R., Khatua, P., Rudra, A., Kapon, E., Malzer, S.,... Bansal, B. (2015). Measurements of the Electric Field of Zero-Point Optical Phonons in GaAs Quantum Wells Support the Urbach Rule for Zero-Temperature Lifetime Broadening. Physical Review Letters, 114. https://dx.doi.org/10.1103/PhysRevLett.114.047402

MLA:

Bhattacharya, Rupak, et al. "Measurements of the Electric Field of Zero-Point Optical Phonons in GaAs Quantum Wells Support the Urbach Rule for Zero-Temperature Lifetime Broadening." Physical Review Letters 114 (2015).

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