Preparation And Performance Test Of Molybdenum Disulfide Field Effect Transistor

With the development of large-scale integrated circuit technology,the size of microelectronic devices gradually decreases and traditional semiconductor materials represented by silicon and germanium series will reach the performance limit,so it is necessary to find a new semiconductor material.Two-dimensional nanomaterials have unique electrical properties,can support ultra-high-speed flow of free electrons.As a member of two-dimensional nanomaterials,molybdenum disulfide(MoS2)like graphene has similar carrier mobility,large switching ratio,low power consumption,lamellar structure.Monolayer MoS2 has a direct bandgap of about 1.8 eV,which has great applications in the microelectronics field.In this paper,we use Molecules epitaxy equipment(LMBE)to fabricate MoS2 thin film on SiO2 substrate and Al2O3 substrate.Meanwhile,the effects of deposition conditions on the microstructure,thickness and optical properties of the films were systematically studied and the preparation parameters of the films were optimized.Finally,a back-gate molybdenum disulfide field-effect transistor was fabricated on a SiO2/Si substrate using an integrated circuit process and it's electrical and optoelectronic characteristics were tested.The main work results are as follows:(1)The effects of deposition conditions(number of laser pulses,laser pulse frequency,pulse energy,etc.)on the surface morphology,film thickness and crystal quality of molybdenum disulfide films were investigated.The results show that the molybdenum disulfide film is a thermodynamically stable 2H-MoS2,while the S content is less than the Mo content and there is an aerobic vacancy.When the laser energy is 100 mJ and the frequency is 6 Hz,the film quality is the best.When the laser with a pulse energy of 50 mJ,approximately 1200 pulses can deposit a single-layer MoS2 film.(2)The effect of sub.strate temperature on the microsttucture and optical properties of a single-layer MoS2 thin film was investigated.The results show that the MoS2 thin film has the best surface morphology,crystalline quality,light-absorbing properties and luminescent properties at 800°C.(3)A back gated molybdenum disulfide field effect transistor was fabricated using an integrated circuit process.Tte test results show that the electron mobility of the device is about 4,63 cm2/V-1S-1.Moreover,the device has good photoelectric characteristics.The photocurrent and light intensily have a linear relationship and the photo responsivity is about 0.06 mAW-1.