Zhu S, Zheng W, Lu X, Huang F. Temperature-dependent optical phonon shifts and splitting in cubic
10BP,
natBP, and
11BP crystals.
OPTICS LETTERS 2021;
46:4844-4847. [PMID:
34598214 DOI:
10.1364/ol.439751]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 08/30/2021] [Indexed: 06/13/2023]
Abstract
The infrared reflectance spectrum of cubic boron phosphide (BP) single crystals shows a very narrow Reststrahlen band, indicating a small TO-LO (transverse optical-longitudinal optical) splitting. To study the phonon thermal behavior of the TO(Γ) and the LO(Γ) of 10BP, natBP, and 11BP bulk single crystals, temperature-dependent infrared reflectance spectroscopy in 85-500 K is applied here. As the temperature increases, the Reststrahlen band broadens. The frequencies of the TO(Γ) and the LO(Γ) exhibit nonlinear red shifts, and the TO-LO splitting gradually increases. Our research found that thermal expansion plays a leading role at low temperatures while phonon anharmonicity gradually takes place at high temperatures.
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