Strain effect in aGaAs−In0.25Ga0.75As−Al0.5Ga0.5Asasymmetric quantum wire

Y. Fu, M. Willander, W. Lu, X. Q. Liu, S. C. Shen, C. Jagadish, M. Gal, J. Zou, D. J. H. Cockayne
2000 Physical Review B (Condensed Matter)  
We report a theoretical investigation of the strain effects on the electronic energy band in a GaAs-In 0.25 Ga 0.75 As-Al 0.5 Ga 0.5 As asymmetric quantum wire formed in a V-grooved substrate. Our model is based on the sp 3 s* tight-binding model. It includes different spatial distributions of the lattice-mismatchinduced strain. We solve numerically the tight-binding Hamiltonian through the local Green's function from which the electronic local density of states ͑LDOS͒ is obtained. The detailed
more » ... energy band structure ͑discrete localized states and energy bands of extended states͒ and the spatial distribution of the eigenfunctions ͑wave function amplitude of nondegenerate states or sum of the wave function amplitudes of degenerate states͒ are directly reflected in the LDOS. Spatial mapping of the LDOS's shows a reduction of the lowest excitation energies in different regions of the system when the local lattice structure of the In 0.25 Ga 0.75 As layer relaxes from completely strained to completely relaxed. By comparing the calculated results with photoluminescence measurement data, we conclude that the strain in the In 0.25 Ga 0.75 As layer relaxes linearly from the heterointerface with the Al 0.5 Ga 0.5 As buffer layer to the heterointerface with the top GaAs layer. PHYSICAL REVIEW B 15 MARCH 2000-II VOLUME 61, NUMBER 12 PRB 61
doi:10.1103/physrevb.61.8306 fatcat:jraod3frvnbkhl6fyjpc5mx7ye