tailieunhanh - Aemimetal insulator phase transition in a GaSb/InAs heterostructure

In this study, the authors will show that a semimetal-insulator phase transition may take place in the GaSb/InAs heterostructures due to the exciton pairing between the electrons and holes in the system. In the heterostructure, the top of the valence band of the InAs layer is higher than the bottom of the conduction band of the GaSb layer. | JOURNAL OF SCIENCE OF HNUE DOI Mathematical and Physical Sci. 2016 Vol. 61 No. 7 pp. 98-105 This paper is available online at http SEMIMETAL-INSULATOR PHASE TRANSITION IN A GaSb InAs HETEROSTRUCTURE Nguyen The Lam Faculty of Physics Hanoi Pedagogical University No. 2 Abstract. In this study the authors will show that a semimetal-insulator phase transition may take place in the GaSb InAs heterostructures due to the exciton pairing between the electrons and holes in the system. In the heterostructure the top of the valence band of the InAs layer is higher than the bottom of the conduction band of the GaSb layer. When the Fermi energy level of the system is higher than the bottom of the conduction band of the GaSb layer and lower than the top of the valence band of the InAs layer the system has both electrons and holes and is considered to be a semimetal system. The theoretical calculations for the band gap and the simulation by CASTEP of the electronic structure and density of state in the heterostructrure also indicate that there is a dielectric gap near the Fermi energy level and the semimetal-insulator occurred. These results are in good agreement with the experimental data. Keywords Semimetal-insulator phase transition GaSb InAs heterostructure electronic structure GaSb InAs. 1. Introduction The heterojunction is the interface between two layers of the different semiconductors. These semiconductors have unequal band gaps. Heterojunctions have a lot of advantages for application of the electronic energy bands in devices such as semiconductor lasers solar cells diode and transistors. The behavior of semiconductor heterojunctions depend directly on the alignment of the energy bands at the interface. Semiconductor heterojunctions can be organized into three types straddling gap type I staggered gap type II and broken gap type III . The GaSb InAs hetrostructure has staggered gap and is applied for many devices 1 2 . In .