Two-dimensional semiconductors have attracted immense research interests owing to their intriguing properties and promising applications in electronic and optoelectronic devices.However,the performance of these device...Two-dimensional semiconductors have attracted immense research interests owing to their intriguing properties and promising applications in electronic and optoelectronic devices.However,the performance of these devices is drastically hindered by the large Schottky barrier at the electric contact interface,which is hardly tunable due to the Fermi level pinning effect.In this review,we will analyze the root causes of the contact problems for the two-dimensional semiconductor devices and summarize the strategies on the basis of different contact geometries,aiming to lift out the Fermi level pinning effect and achieve the ohmic contact.Moreover,the remarkable improvement of the device performance thanks to these optimized contacts will be emphasized.At the end,the merits and limitations of these strategies will be discussed as well,which potentially gives a guideline for handling the electric contact issues in two-dimensional semiconductors devices.展开更多
The electronic structures and magnetic properties of strained monolayer MnPSe3 are investigated sys- tematically via first-principles calculations. It is found that the magnetic ground state of monolayer MnPSe3 can be...The electronic structures and magnetic properties of strained monolayer MnPSe3 are investigated sys- tematically via first-principles calculations. It is found that the magnetic ground state of monolayer MnPSe3 can be significantly affected by biaxial strain engineering, while the semiconducting char- acteristics are well-preserved. Owing to the sensitivity of the magnetic coupling towards structural deformation, a biaxial tensile strain of approximately 13% can lead to an antiferromagnetic （AFM）- ferromagnetic （FM） transition. The strain-dependent magnetic stability is mainly attributed to the competition of the direct AFM interaction and indirect FM superexchange interaction between the two nearest-neighbor Mn atoms. In addition, we find that FM MnPSe3 is an intrinsic half semiconductor with large spin exchange splitting in the conduction bands, which is crucial for the spin-polarized carrier injection and detection. The sensitive interdependence among the external stimuli, electronic structure, and magnetic coupling makes monolayer MnPSe3 a promising candidate for spintronics.展开更多
基金supported by the National Natural Science Foundation of China(21825103,51727809)the National Basic Research Program of China(2015CB932600)the Fundamental Research Funds for the Central University(2019kfy XMBZ018)
文摘Two-dimensional semiconductors have attracted immense research interests owing to their intriguing properties and promising applications in electronic and optoelectronic devices.However,the performance of these devices is drastically hindered by the large Schottky barrier at the electric contact interface,which is hardly tunable due to the Fermi level pinning effect.In this review,we will analyze the root causes of the contact problems for the two-dimensional semiconductor devices and summarize the strategies on the basis of different contact geometries,aiming to lift out the Fermi level pinning effect and achieve the ohmic contact.Moreover,the remarkable improvement of the device performance thanks to these optimized contacts will be emphasized.At the end,the merits and limitations of these strategies will be discussed as well,which potentially gives a guideline for handling the electric contact issues in two-dimensional semiconductors devices.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 51671142, U1632152, and 51661145026） and the Key Project of Natural Sci- ence Foundation of Tianjin City （Grant No. 16JCZDJC37300）.
文摘The electronic structures and magnetic properties of strained monolayer MnPSe3 are investigated sys- tematically via first-principles calculations. It is found that the magnetic ground state of monolayer MnPSe3 can be significantly affected by biaxial strain engineering, while the semiconducting char- acteristics are well-preserved. Owing to the sensitivity of the magnetic coupling towards structural deformation, a biaxial tensile strain of approximately 13% can lead to an antiferromagnetic （AFM）- ferromagnetic （FM） transition. The strain-dependent magnetic stability is mainly attributed to the competition of the direct AFM interaction and indirect FM superexchange interaction between the two nearest-neighbor Mn atoms. In addition, we find that FM MnPSe3 is an intrinsic half semiconductor with large spin exchange splitting in the conduction bands, which is crucial for the spin-polarized carrier injection and detection. The sensitive interdependence among the external stimuli, electronic structure, and magnetic coupling makes monolayer MnPSe3 a promising candidate for spintronics.
