Abstract
A new calculation is made of the quantum-well intersubband absorption by electrons that occupy valleys with ellipsoidal constant-energy surfaces. Application of the results to the special case of spherical-valley materials yields excellent agreement with recent experimental results for GaAs quantum wells. According to the calculation, strong intersubband absorption is exhibited by ellipsoidal-valley quantum wells in indirect-band-gap As and Sb alloys, and both materials have the advantage over GaAs of being able to absorb light incident normal to the quantum-well plane. For a wavelength of 10 μm, sheet concentration of 7.6× , and a linewidth of 11 meV, the calculated fractional absorptions for normally incident light on a (111) As and (100) Sb quantum well are 0.000 73 and 0.0022, respectively, independent of the azimuthal angle of polarization. The absorption is stronger for Sb than for As because the ellipsoid eccentricity is greater for L valleys than for X valleys in these materials.
- Received 18 December 1989
DOI:https://doi.org/10.1103/PhysRevB.41.7559
©1990 American Physical Society