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The Theoretical Optical Gain of Ge 1− x Sn x Nanowires
Author(s) -
Xiong Wen,
Fan Wei-Jun,
Song Zhi-Gang,
Tan Chuan-Seng
Publication year - 2020
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201900704
Subject(s) - nanowire , materials science , semiconductor , band gap , direct and indirect band gaps , photonics , optoelectronics , germanium , net gain , effective mass (spring–mass system) , diode , absorption (acoustics) , electron , nanotechnology , physics , silicon , amplifier , cmos , quantum mechanics , composite material
The electronic structures of Ge 1− x Sn x nanowires at the direct Γ‐valley and indirect L ‐valley is calculated using k · p effective‐mass theory, and the results demonstrate that Ge 1− x Sn x nanowires with large diameter and Sn content can easily be engineered to be the direct‐band‐gap semiconductor. Furthermore, the optical gain of Ge 1− x Sn x nanowires as functions of the injected electron concentration and diameter are obtained. Compared with pure Ge nanowires, a remarkable peak gain can appear in Ge 1− x Sn x nanowires even though the injected electron concentration decreases. This is because incorporating Sn into Ge can reduce even reverse the energy difference of minimum bandgap between the direct Γ‐valley and indirect L ‐valley. Therefore, considering the free‐carrier absorption loss, one can achieve a positive net peak gain in Ge 1− x Sn x nanowires, which indicates that Ge 1− x Sn x nanowires can be used as an ideal laser diode candidate in the field of Si‐photonics.