Use Of Micro-Photoluminescence As A Contactless Measure Of The 2d Electron Density In A Gaas Quantum Well

We compare micro-photoluminescence (mu PL) as a measure of the electron density in a clean, two-dimensional (2D) system confined in a GaAs quantum well (QW) to the standard magneto-transport technique. Our study explores the PL shape evolution across a number of molecular beam epitaxy-grown samples with different QW widths and 2D electron densities and notes its correspondence with the density obtained in magneto-transport measurements on these samples. We also measure the 2D density in a top-gated quantum well sample using both PL and transport and find that the two techniques agree to within a few percent over a wide range of gate voltages. We find that the PL measurements are sensitive to gate-induced 2D density changes on the order of 10(9) electrons/cm(2). The spatial resolution of the PL density measurement in our experiments is 40 mu m, which is already substantially better than the millimeter-scale resolution now possible in spatial density mapping using magneto-transport. Our results establish that mu PL can be used as a reliable high spatial resolution technique for future contactless measurements of density variations in a 2D electron system. Published by AIP Publishing.