Study On The Electrical Properties Of Two-dimensional Planar Heterojunction Device

Since the first transistor has fabricated,it has greatly promoted the development of electronic technology.After decades of rapid development,the development speed of electronic technology has gradually slowed down,because the silicon material has approached its physical limit,and it is impossible to fabricate high-performance devices based on silicon material.Therefore,finding a new material to replace silicon is an effective method.Since the successful fabrication of graphene,researchers have paid more and more attention to the exploration of two-dimensional（2D）materials.With the deepening of the exploration of 2D materials,2D materials are considered potential materials for the next generation of nanoelectronics devices due to their excellent photoelectric properties.Heterojunctions based on 2D materials have been widely used in many fields due to their novel and excellent properties.At present,heterojunctions can be divided into vertical heterojunctions and planar heterojunctions according to the construction position,and the planar heterojunctions can be divided into homogeneous junctions and heterojunctions.Compared with the 2D vertical heterojunctions,the 2D planar heterojunctions have stronger structural stability because it is formed by covalent bonds between atoms,and the 2D planar heterojunctions have a thinner thickness,thus it has a very broad prospect in the application of future electronic devices.Consequently,in this paper,the 2D planar heterojunction is mainly studied,and two kinds of planar heterojunction are constructed by using the first principles,and investigate the performance of devices based on planar heterojunction,which provides a theoretical basis for the study of 2D planar heterojunction.The work content of this paper is as follows:First,the graphene/Mo SSe planar heterojunction structures with different contact surfaces have constructed by using first principles and built an asymmetric electrode device based on the heterostructure.Calculating the binding energy,local projected state density,electron effective potential and I-V curve for three different contact interfaces,the results show that the stability of different contact interface structures is different,no ohmic contact is formed,and the contact resistance is also different（0.55e V,0.65e V and 0.56e V）.After doping regulation,the contact resistance of the three structures is significantly reduced and ohmic contact can be formed.In addition,the I-V curves calculated under the same bias voltage show that the three structures exhibit very different characteristics,such as near-linear relationships and negative differential resistance effect.This work provides a new reference for designing new electronic devices.Secondly,a planar heterojunction structure based on phosphorus boride and a 5nm double-gate metal-oxide-semiconductor transistor have been constructed in this work.The transmission characteristics of the transistor,the influence of doping and Underlap structure on the transmission characteristics of the transistor are studied.The results show that the n/p type MOSFET can obtain the maximum on-state current（1460μA/μm and 1697.96μA/μm）with the doping concentration N_S=N_D=0.01/1×10¹⁵cm^-2,and the performance of the p-type MOSFET is better than that of the n-type MOSFET.However,the on-state current of the transistor is improved by doping,and the gate control ability is not improved.The minimum SS of n/p type MOSFET is 94.28 m V/dec and 104.5m V/dec.Therefore,the transistor structure is optimized by using different lengths of Underlap structure.The results show that the longer the Underlap structure,the performance of the transistor is not improved,but has a great loss.Only when the length is 1nm,the gate control ability of the transistor is greatly improved,and the SS of the p-type MOSFET is reduced to 49.8m V/dec.In addition,the properties of the transistors at different lengths are also studied.The results show that the MOS transistors based on phosphorus boride can achieve smaller sizes.This study fills the deficiency of phosphorus boride application in transistors and provides a reference for the development of electronic devices.Thirdly,the blue phosphorus and copper have been used to construct a planar heterojunction and study the transmission characteristics of the Schottky transistor based on planar heterojunction.The results show that there are metallization and a small Schottky barrier（0.52e V）at the contact interface of the Cu/Blue P heterojunction.Investigated the on-state current of 5.1nm Blue P Schottky barrier field-effect transistors with different dielectrics（Si O₂,Al₂O₃,Y₂O₃ and La₂O₃）using quantum transport simulations to study the performance of transistors.The results show that the Blue P Schottky barrier transistor with four kinds of dielectrics meets the requirements of the international semiconductor technology roadmap for the off-state current（0.1μA/μm）of high-performance devices.The on-state current（1120μA/μm）of the Blue P Schottky barrier transistor only with La₂O₃ meets the requirements of the international semiconductor technology roadmap.This will provide a reference for the design of the Blue P Schottky barrier field effect transistor.