A silicon bi-layer system

This report concerns front and back-gated SiO2/Si/SiO2 quantum wells formed by fabricating MOSFETʹs on (100) SIMOX silicon-on-insulator substrates. By examining the magneto-transport properties of samples with various well-widths, we demonstrate that such structures are suitable for investigating correlation effects under various regimes of behaviour. We find that an View the MathML source quantum well behaves as a single layer of two-dimensional electrons at accessible gate voltages. We present convincing evidence that the back-gate provides unique control over the valley splitting unavailable in conventional Si MOSFETʹs by shifting the wave function between the two Si/SiO2 interfaces, as first suggested by Ouisse et al. (Physica B 249–251 (1998) 731). A slightly wider View the MathML source quantum well behaves as a strongly-coupled bi-layer system, where the valley splitting is different in each layer. A very wide View the MathML source-wide quantum well behaves as two totally independent two-dimensional electron layers.