J. Zeman

Interwell Radiative Recombination in the Presence of Random Potential Fluctuations in GaAs/AlGaAs Biased Double Quantum Wells

The interwell radiative recombination from biased double quantum wells (DQW) in pin GaAs/AlGaAs heterostructures is investigated at different temperatures and external electrical fields. The luminescence line of interwell recombination of spatially separated electron-hole pairs exhibits systematic narrowing with temperature increase from 4.5 to 30 K. A theoretical model is presented which explains the observed narrowing in terms of lateral thermally activated tunneling of spatially separated e-h pairs localized by random potential fluctuations in the quantum wells.

Spectroscopic Study of the Interface and Band Alignment at the GaInP(Partially Ordered)/GaAs Heterojunction under High Pressure and High Magnetic Field

The semiconducting alloy Ga0.5In0.5P grown epitaxially on a GaAs substrate forms a rather unique system in which not only the band gap is tunable by varying the degree of CuPt ordering in the Ga0.5In0.5P but also the band alignment can be varied from type Ito type II. The band alignment has been found to have an important influence on the optoelectronic properties of the Ga0.51n0.5P layer in terms of the efficiency of photoluminescence upconversion at the Ga0.5In0.5P /GaAs interface and the observation of quantum well emission from Ga0.5In0.5P/GaAs/-Ga0.5In0.5P structure. In this paper we shall demonstrate how the band offset and alignment in such heterostructures can be manipulated and measured with meV resolution by combining spectroscopic measurements with high pressure and high magnetic field. In addition, the magnetic length can be used as a “nanometer-stick” in probing the size of type II domains in samples where most of the interface is of type I except for tiny islands of more ordered domains.