Recombination of two-dimensional electrons with free light and heavy holes in AlxGa1-xAs-GaAs single heterojunctions in a magnetic field.

Abstract

Landau-level oscillations are observed in the photoluminescence from an ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As-GaAs single heterojunction in an applied magnetic field. Extrapolating the oscillations back to zero field gives the energy of the transition from the two-dimensional (2D) electrons to the free heavy holes (hh1 and hh2) and free light holes (lh) weakly confined in the GaAs active layer. The measured energy separation between hh1 and lh is 1.8 meV, which agrees very well with the calculated value of 2.2 meV. The measured energy separation between hh1 and hh2 is 3.8 meV, in good agreement with the calculated value of 4.4 meV. The 2D electron effective mass was determined to be ${\mathit{m}}_{\mathit{e}}^{\mathrm{*}}$=0.086m. The light-hole effective mass was determined to be ${\mathit{m}}_{\mathrm{lh}}^{\mathrm{*}}$=0.078m, using the GaAs heavy-hole effective mass ${\mathit{m}}_{\mathrm{hh}1}^{\mathrm{*}}$=0.46m as input. The effective mass ${\mathit{m}}_{\mathrm{hh}2}^{\mathrm{*}}$ is approximately the same as ${\mathit{m}}_{\mathrm{hh}1}^{\mathrm{*}}$.