Few electron double quantum dot in an isotopically purified 28Si quantum well

We present a few electron double quantum dot device defined in an isotopically purified 28Si quantum well (QW). An electron mobility of 5.5·104cm2(Vs)-1 is observed in the QW, which is the highest mobility ever reported for a two-dimensional electron system in 28Si. The residual concentration of 29Si nuclei in the 28Si QW is lower than 103ppm, at the verge where the hyperfine interaction is theoretically no longer expected to dominantly limit the T2 spin dephasing time. We also demonstrate a complete suppression of hysteretic gate behavior and charge noise using a negatively biased global top gate.