Polarization-Induced Two-Dimensional electron gas at BeO/ZnO interface

Abstract

Beryllium oxide (BeO) is a unique metal oxide with excellent thermal conductivity and dielectric strength. BeO tends to grow as wurtzite single crystals via atomic layer deposition, leading to the strong polarization of heterostructures with various substrates. We demonstrated the formation of a polarization-induced two-dimensional electron gas (2DEG) at a BeO/ZnO heterostructure interface. The polarity discontinuity induced by the c-axis-grown crystalline BeO film caused charges to accumulate on the ZnO substrate. The sheet carrier concentration and mobility of the BeO/ZnO heterostructure were 2.0 × 1014 cm−2 and 22 cm2·V−1·s−1 at room temperature, respectively, approximately 57 times and 11 times greater than those of bare ZnO, respectively. In addition, the carrier concentration was nearly constant over the temperature range of 150 K – 350 K. The 2DEG layers formed via ALD BeO films are possible channel materials for use in various electronic devices such as thin film transistors.