High-density electron gas induced by atomic ordering in undoped Ga/sub 0.5/In/sub 0.5/P/GaAs heterostructure

We investigated two-dimensional properties of electrons accumulated at a long-range ordered Ga/sub 0.5/In/sub 0.5/P/GaAs heterointerface by magneto-photoluminescence (PL) measurements. The disordered Ga/sub 0.5/In/sub 0.5/P/GaAs sample shows a typical GaAs-PL spectrum for the bulk GaAs grown by metalorganic vapor-phase epitaxy. On the other hand, the GaAs-PL spectrum for the ordered sample with order parameter /spl eta/ of 0.30 shows transitions related to a quantized electron state in a triangular potential buried at the heterointerface and emission of the Fermi-edge singularity. The observed PL spectrum for the ordered sample demonstrates that a two-dimensional electron gas is induced at the Ga/sub 0.5/In/sub 0.5/P/GaAs heterointerface. In magneto-PL measurements, anisotropy of the reduced mass between parallel and perpendicular to the heterointerface was confirmed. Furthermore, the clear optical Shubnikov-de Haas oscillation was found in PL transition energy under the perpendicular magnetic field. The sheet-carrier density of 2DEG is deduced from the period of the observed Shubnikov-de Haas oscillation to be /spl sim/1.20/spl times/10/sup 12/ cm/sup -2/.