Spatial confinement of electrons in ultrathin layers of indirect gap Si, SiGe and SiGeC leads to a spread in the momentum of electrons, so that the envelope function of electrons possesses a sizeable Fourier component at k₀, the wave vector for conduction band minima in the materials. Under this situation, the matrix elements for interband transition may be appreciably enhanced. In this work, the matrix elements for quasi-direct non phonon transitions have been evaluated for Si quantum wells, coupled Si/SiGe quantum wells and SiGeC/Si quantum wells. The absorption coefficient, (alpha) , for all these cases, are then calculated to examine the potential of the structures as emitters. The values of (alpha) are enhanced in quantum wells; however to achieve values of (alpha) , as large as in direct gap GaAs, quantum dots need be considered.

Date Published: 25 September 2001
PDF: 6 pages
Proc. SPIE 4417, Photonics 2000: International Conference on Fiber Optics and Photonics, (25 September 2001); doi: 10.1117/12.441337

Published in SPIE Proceedings Vol. 4417:
Photonics 2000: International Conference on Fiber Optics and Photonics
S. K. Lahiri; Ranjan Gangopadhyay; Asit K. Datta; Samit K. Ray; B. K. Mathur; S. Das, Editor(s)