Inequivalence of normal and inverted interfaces of molecular-beam epitaxy grown AlGaAs/GaAs quantum wells

Abstract

Normal and inverted interfaces of GaAs/AlGaAs heterostructures are studied by comparing the luminescence of quantum wells (QWs) grown by molecular-beam epitaxy with a 10–300 s growth interruption either at one or both of the interfaces. The influence of growth interruption time on the incorporation of shallow impurities and traps and on the variation of the interface structure is investigated. GaAs surfaces become appreciably smoother with increasing interruption time, and increasing incorporation of shallow impurities, but no incorporation of traps at the growth surface is observed. At AlGaAs surfaces, the concentration of traps strongly increases with growth interruption time, but the surface does not become smoother. Additionally strong accumulation of shallow impurities at the inverted GaAs-on-AlGaAs interface is directly visualized.

Temperature dependence of current–voltage characteristics of terahertz quantum-well photodetectors

“…The vertical transport of excited carriers has a direct influence on the performance of infrared detectors [14]. These excited carriers experience various scattering events due to optical phonons, electronelectron interaction, impurities [15] and the well barrier interfaces [16] when they are flowing through the multi quantum-well structures. Vertical transport in GaAs/AlGaAs barrier structures has been studied by measuring the vertical current as a function of temperature at different bias voltages [17].…”

The improved inverted AlGaAs/GaAs interface: its relevance for high-mobility quantum wells and hybrid systems

“…Traditionally, the inverted interface is said to have inferior quality compared to the well-established MODFET [18][19][20]. Despite improved inverted 2DEG mobilities by applying graded superlattices at the interface [21,22], increased setback layers [23], top- [24] and back gating [25], this hierarchical order remained unchanged.…”