Valley Splitting in Silicon from the Interference Pattern of Quantum Oscillations

We determine the energy splitting of the conduction-band valleys in two-dimensional electrons confined in silicon metal oxide semiconductor Hall-bar transistors. These silicon metal oxide semiconductor Hall bars are made by advanced semiconductor manufacturing on 300 mm silicon wafers and support a two-dimensional electron gas of high quality with a maximum mobility of 17.6 ?? 103 cm2/Vs and minimum percolation density of 3.45 ?? 1010 cm???2. Because of the low disorder, we observe beatings in the Shubnikov???de Haas oscillations that arise from the energy splitting of the two low-lying conduction band valleys. From the analysis of the oscillations beating patterns up to T = 1.7 K, we estimate a maximum valley splitting of ??EVS = 8.2 meV at a density of 6.8 ?? 1012 cm???2. Furthermore, the valley splitting increases with density at a rate consistent with theoretical predictions for a near-ideal semiconductor-oxide interface.