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Title: Uniaxial strain effect on the electronic and optical properties of wurtzite GaN-AlGaN quantum-well lasers
Authors: Yeo, Y.C. 
Chong, T.C. 
Li, M.-F. 
Keywords: Gallium nitride
Optical materials/devices
Quantum wells
Semiconductor lasers
Issue Date: Nov-1998
Citation: Yeo, Y.C.,Chong, T.C.,Li, M.-F. (1998-11). Uniaxial strain effect on the electronic and optical properties of wurtzite GaN-AlGaN quantum-well lasers. IEEE Journal of Quantum Electronics 34 (11) : 2224-2232. ScholarBank@NUS Repository.
Abstract: The valence subband structures of uniaxial-strained wurtzite (WZ) GaN-AlGaN quantum wells (QW's) are calculated using multiband effective-mass theory. The optical gain is investigated using a numerical approach in which we account for the subband structure modification and mixing due to the anisotropic strain in the QW plane. We show that the mixing of the HH and LH bases in the uniaxial-strained (0001) GaN-AlGaN QW decouples |X〉 and |Y〉 at the Γ point, giving two topmost subbands, Y1 and X1, which can be more widely separated than the HH1 and LHI subbands in the biaxial-strained (0001) GaN-AlGaN QW. We resolve the states of the subband dispersion in terms of the |X〉, |Y〉, and \Z〉 bases, and show the compositional variation as a function of the in-plane wavevector. Under uniaxial strain, it is possible to exploit the existence of the preferred symmetry at the valence band maximum and the reduced band-edge density-of-states due to the anisotropic in-plane energy dispersion to achieve lower transparency carrier and current densities and higher differential gain in comparison with a pseudomorphic biaxial-strained QW. We show that, for a QW laser structure with the optical cavity along the x axis, uniaxial compressive strain in the y direction shows greater improvement than the uniaxial tensile strain in the x direction of the same magnitude. Thus, a suitable uniaxial strain could be used to improve the threshold performance of WZ GaN-based QW lasers.
Source Title: IEEE Journal of Quantum Electronics
ISSN: 00189197
DOI: 10.1109/3.726618
Appears in Collections:Staff Publications

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