First-principles calculations are performed to explore the possibility of generating the two-dimensional electron gas(2 DEG) at the interface between LaGaO_3/KTaO_3 and NdGaO_3/KTaO_3(001) heterostructures. Two differ...First-principles calculations are performed to explore the possibility of generating the two-dimensional electron gas(2 DEG) at the interface between LaGaO_3/KTaO_3 and NdGaO_3/KTaO_3(001) heterostructures. Two different models —i.e., the superlattice model and the thin film model — are used to conduct a comprehensive investigation of the origin of charge carriers. For the symmetric superlattice model, the LaGaO_3(or NdGaO_3) film is nonpolar. The 2 DEG with carrier density on the order of 1014 cm^(-2) originates from the Ta dxy electrons contributed by both LaGaO_3(or NdGaO_3) and KTaO_3. For the thin film model, large polar distortions occur in the LaGaO_3 and NdGaO_3 layer, which entirely screens the built-in electric field and prevents electrons from transferring to the interface. Electrons of KTaO_3 are accumulated at the interface, contributing to the formation of the 2 DEG. All the heterostructures exhibit conducting properties regardless of the film thickness. Compared with the Ti dxy electrons in SrTiO_3-based heterostructures, the Ta dxy electrons have small effective mass and they are expected to move with higher mobility along the interface. These findings reveal the promising applications of 2 DEG in novel nanoelectronic devices.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2013CB632506)the National Natural Science Foundation of China(Grant Nos.11374186,51231007,and 51202132)
文摘First-principles calculations are performed to explore the possibility of generating the two-dimensional electron gas(2 DEG) at the interface between LaGaO_3/KTaO_3 and NdGaO_3/KTaO_3(001) heterostructures. Two different models —i.e., the superlattice model and the thin film model — are used to conduct a comprehensive investigation of the origin of charge carriers. For the symmetric superlattice model, the LaGaO_3(or NdGaO_3) film is nonpolar. The 2 DEG with carrier density on the order of 1014 cm^(-2) originates from the Ta dxy electrons contributed by both LaGaO_3(or NdGaO_3) and KTaO_3. For the thin film model, large polar distortions occur in the LaGaO_3 and NdGaO_3 layer, which entirely screens the built-in electric field and prevents electrons from transferring to the interface. Electrons of KTaO_3 are accumulated at the interface, contributing to the formation of the 2 DEG. All the heterostructures exhibit conducting properties regardless of the film thickness. Compared with the Ti dxy electrons in SrTiO_3-based heterostructures, the Ta dxy electrons have small effective mass and they are expected to move with higher mobility along the interface. These findings reveal the promising applications of 2 DEG in novel nanoelectronic devices.
