Abstract

While valence subband mixing significantly affects the electroabsorption spectra, previous theories have ignored the contribution of the linear k terms in the Luttinger Hamiltonian.¹ Here we study the effect of these terms by first solving the 4x4 effective mass equation for the two lowest valence subbands and then generating the exciton binding energies and wavefunctions. We find that the linear k terms couple hh 1 and lhA levels even at k = 0 so that the hh1 → cl 1s exciton transition is permitted for TM polarized light. The latter observation agrees qualitatively with experimental results.2 Further, since the linear k terms couple the exciton wavefunctions, the hh 1 and lh1 transition peaks do not cross. We expect that additional features of the linear k term induced subband mixing on the electroabsorption spectra of strained GaAs/AlGaAs quantum wells, particularly as regards selection rules, oscillator strength ratios and polarization dependence, will be observable at low temperatures.

© 1993 Optical Society of America