Fabrication Of Molybdenum Disulfide Field Effect Transistor For Detection Of Biological Molecules

Human genome sequencing has extremely important significance to the realization of personalized disease detection, the essence of which is the detection of biological molecules. Integrated fabrication of field effect transistors and solid state nanopore is most likely to achieve single base recognition technology. And the key technology to realize the integration of the four electrodes is the preparation of the field effect transistor. There are a lot of materials used in nano semiconductor devices. Two-dimensional molybdenum disulfide is attractively emerging as a material complementary to graphene due to its large direct band gap, high room-temperature current on/off ratios and ultra high sensitivity for single layer of MoS2, which satisfied the demands for detection of biological molecules.This paper mainly introduces the fabrication method of field effect transistor based on MoS2 films. Fabrication of MoS2 field effect transistor mainly comprises the following steps: preparation of silicon nitride; expatiation of the MoS2 coatings; fabrication of metal electrode. In the preparation process, the transfer of MoS2 is the key technology, which is very difficult. However, it is found that the solid state field effect transistor prepared by this method has Schottky barrier. There is large contact resistance between the metal electrode and the thin film of MoS2, which greatly influences the performance of the field effect transistor. And field effect transistor is prepared to satisfied the demands for detection of biological molecules, which need to study the application of liquid phase field effect transistor, so we need to improve the preparation method and process.After the preparation of field effect transistors, a new method is proposed to fabricate the field effect transistors suitable for liquid phase. Preparation of molybdenum disulfide field effect transistorssuitable for liquid phase mainly comprises the following steps:preparation of silicon nitride; fabrication of metal electrode; expatiation of the MoS2 coatings.The molybdenum disulfide and metal source and drain was connected by using FIB to carry on the metal plating platinum. The sequence of preparation process is changed between the preparation of metal electrode and MoS2 film. Then the gate voltage is applied through the salt solution. This change can improve the performance of MoS2 FET greatly, which is expected to be widely used in the field of preparation of bio-sensing devices. We performed electrical characterization of monolayer MoS2 field-effect transistors at room temperature. We found that the resistance of transistor in wet condition is smaller than that in air. Also, we demonstrate that with the increasing of the liquid-gate voltage, the slope of the Ids-Vds characteristics become higher. It is conformed that MoS2 FET has superior performance, which can be used for the future combination with solid-state nanopore for bio-molecular detection, to achieve the purpose of single base identification.The experiments were conducted to detect biological molecules using the MoS2 nanopore, the experimental results show that:(1) The ?-DNA molecules pass through the MoS2 nanoporewith with three different forms, which corresponds to different ion current signal; (2) When the liquid pool is applied from the positive voltage to the negative voltage, the blocking signal of the DNA molecule is changed from the peak to the ascending peak; (3) With the detection of 20 poly (dA) using small MoS2 nanopore, we found that the signal-to-noise ratio can be improvedand aperture time has been extended for further analysis to increase the possibility of single base identification.