Two-dimensional electron gas in Zn-polar ZnMgO/ZnO heterostructure grown by metal-organic vapor phase epitaxy

We report the formation of two-dimensional electron gas 2DEG at the Zn1−xMgxO/ZnO interface grown by metal-organic vapor phase epitaxy on sapphire substrates. The existence of the 2DEG is confirmed by the observation of Shubnikov–de Haas oscillations and the integer quantum Hall effect. In particular, the Zn0.8Mg0.2O/ZnO heterostructure shows a high Hall mobility of 2138 cm2 /V s with a carrier sheet density of 3.511012 cm−2 at 1.4 K. We attribute the origin of 2DEG to be the donor states on ZnMgO surface. The dependence of carrier sheet density of 2DEG on ZnMgO layer thickness and Mg composition x are also investigated.This work was supported by the Singapore Agency for Science, Technology, and Research A*STAR, under SERC Grant No. 0521260095 and Infuse Project No. I01-0911-06