单层二硫化钼背栅场效应晶体管的电学及光电特性研究

发布时间：2018-01-10 21:29

本文关键词：单层二硫化钼背栅场效应晶体管的电学及光电特性研究　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：过去半个世纪以来,以硅基半导体材料为基础的大规模集成电路技术得到了飞速发展,随着单位面积上半导体器件密度的不断增加,半导体器件正逐渐接近其尺寸的理论极限,“后摩尔时代”即将到来。二维材料以其优越的理化性能、高载流子迁移率及能带可调等特点,成为最有可能在微电子和光电子等领域引发革命的材料之一。二硫化钼薄膜是典型的二维层状结构材料,单层二硫化钼具有直接带隙,多层二硫化钼具有间接带隙,有望成为硅基半导体的替代材料。此外,基于二硫化钼的各种性能优异的光电传感器、气体传感器及柔性器件在现代医疗、环境、机械及农业等方面都有较大的应用价值。在国家自然基金(No.51675246)的资助下,采用一种新的方法制备了基于二硫化钼的悬置场效应晶体管,并与传统的非悬置器件作对比。单层二硫化钼薄膜样品是采用化学气相沉积(CVD)法制备,将单层二硫化钼薄膜转移到预先图形化处理的带电极衬底上,构成悬置和非悬置的单层二硫化钼场效应晶体管。光学显微镜用来直接观察样品与电极接触情况,拉曼(Raman)光谱用来表征样品层数及质量,原子力显微镜(AFM)用来表征样品表面质量及厚度。对悬置和非悬置场效应晶体管输出特性曲线和转移特性曲线分析发现,室温下悬置器件的载流子迁移率比非悬置器件有4倍的提升,随着温度升高悬置器件的载流子迁移率升高幅度远大于非悬置器件的升高幅度。这主要是因为低温时带电杂质产生的库伦散射是限制其载流子迁移率的主要因素,温度升高时器件载流子迁移率主要被表面声子散射限制。器件的转移特性曲线出现较大的磁滞现象,给器件性能带来较大的不稳定。室温条件下悬置器件的磁滞现象强度小于非悬置器件的强度,随着温度的升高两器件中的磁滞现象强度都出现不同程度的增大。这主要是由于器件上吸附的杂质中的电子转移到沟道材料中充当电荷载流子,导致磁滞现象的发生,高温条件下电子通过接触面间肖特基势垒的几率大大增加,导致磁滞现象的增强。在测试器件电学性能过程中发现悬置器件由于栅氧化层较薄,器件会出现击穿现象。这主要是因为硅氧键的键能较弱,在高电场作用下硅氧键断裂导致缺陷在界面集聚,当大量缺陷形成的渗透通道在热损伤作用下形成稳定的传输通道时器件被击穿。二硫化钼场效应晶体管理论性能的研究对基于二硫化钼薄膜的性能优异的晶体管及传感器的实际应用具有较大的促进作用。
[Abstract]:In the past half century, large scale integrated circuit (LSI) technology based on silicon based semiconductor materials has been developed rapidly, with the increasing density of semiconductor devices per unit area. Semiconductor devices are approaching the theoretical limit of their size and the "post-molar era" is coming. Two-dimensional materials are characterized by their superior physical and chemical properties, high carrier mobility and tunable band. Molybdenum disulfide thin film is a typical two-dimensional layered structure material, monolayer molybdenum disulfide has direct band gap. Multilayer molybdenum disulfide has an indirect band gap and is expected to be an alternative material for silicon based semiconductors. In addition, various excellent photoelectric sensors, gas sensors and flexible devices based on molybdenum disulfide are used in modern medicine and environment. Mechanical and agricultural applications are of great value. Supported by the National Fund for Nature No. 51675246, a new method has been developed for the fabrication of mount field effect transistors based on molybdenum disulfide. The monolayer molybdenum disulfide films were prepared by chemical vapor deposition (CVD) method. The monolayer molybdenum disulfide films were transferred to the pre-patterned substrate with electrodes. The monolayer molybdenum disulfide field effect transistors were constructed. Optical microscope was used to observe the contact between the sample and the electrode. Raman Raman spectroscopy was used to characterize the layer number and mass of the sample. AFM was used to characterize the surface quality and thickness of the samples. The output and transfer characteristic curves of the suspended and unmounted FET were analyzed. The carrier mobility of the mount device at room temperature is 4 times higher than that of the non-mount device. With the increase of temperature, the carrier mobility of the mount device is much higher than that of the non-mounted device. This is mainly because the Coulomb scattering caused by charged impurity at low temperature is the main factor limiting the carrier mobility. . The carrier mobility of the device is mainly limited by surface phonon scattering when the temperature increases. The transfer characteristic curve of the device has a large hysteresis phenomenon. The hysteresis intensity of the mount device is lower than that of the non-mount device at room temperature. With the increase of temperature, the hysteresis intensity of both devices increases in varying degrees, which is mainly due to the transfer of electrons from the impurities in the devices to the channel materials to act as charge carriers. As a result of hysteresis, the probability of electron passing through Schottky barrier between contact surfaces at high temperature is greatly increased. In the process of testing the electrical properties of the device, it is found that the device will break down because of the thin gate oxide layer. This is mainly due to the weak bond energy of the silicon and oxygen bond. Under the action of high electric field, the fracture of SiO2 bond leads to the accumulation of defects at the interface. The device is broken down when the permeable channel formed by a large number of defects forms a stable transmission channel under thermal damage. A study on theoretical Properties of molybdenum disulfide Field effect Transistor based on excellent performance of molybdenum disulfide thin Film. And the practical application of the sensor has a greater role in promoting.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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