Photoluminescence and the gallium problem for highest-mobility GaAs/AlGaAs-based 2d electron gases

Abstract

The quest for extremely high mobilities of 2d electron gases in MBE-grown heterostructures is hampered by the available purity of the starting materials, particularly of the gallium. Here we compare the role of different Ga lots having nominally the highest possible quality on the mobility and the photoluminescence (PL) of modulation doped single interface structures and find significant differences. A weak exciton PL reveals that the purity of the Ga is insufficient. No high mobility can be reached with such a lot with a reasonable effort. On the other hand, a strong exciton PL indicates a high initial Ga purity, allowing to reach mobilities of 15 million (single interface) or 28 million $c{m}^2/Vsec$ (doped quantum wells) in our MBE systems. We discuss possible origins of the inconsistent Ga quality. Furthermore, we compare samples grown in different MBE systems over a period of several years and find that mobility and PL is correlated if similar structures and growth procedures are used.

References in corpus (2)

• Limit to 2D mobility in modulation-doped GaAs quantum structures: How to achieve a mobility of 100 millions
• Mapping an electron wave function by a local electron scattering probe

Cited by in corpus (5)

• Ultra-high quality two-dimensional electron systems
• Working principles of doping-well structures for high-mobility two-dimensional electron systems
• Surface segregation and the Al problem in GaAs quantum wells
• Spatial Mapping of Local Density Variations in Two-dimensional Electron Systems Using Scanning Photoluminescence
• Thin films as practical quantum materials: a status quo and beyond