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

摘要

We report the formation of two-dimensional electron gas (2DEG) at the Zn_(1-x)Mg_xO/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 Zn_(0.8)Mg_(0.2)O/ZnO heterostructure shows a high Hall mobility of 2138 cm~2/V s with a carrier sheet density of 3.51 × 10~(12) 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.