Fabrication And Performance Study Of Flexible Monocrystalline Silicon/Low-Dimensional Nanomaterials And Devices

With the further development of microelectronics technology,the limitations of traditional rigid microelectronics are effectively made up by developing a simple manufacturing process to construct a low cost,portable and flexible performances and novel next-generation electronic materials and devices,which can promote the diversified development of the modern electronic.This paper reported the preparations and flexibility methods of three kinds of flexible materials with micro-nano structure,such as single crystal silicon,graphene and silver nanowires,and explored preparation and performance optimization methods of corresponding flexible device.The main results are as follows:1.Base on the crystallographic characteristics of monocrystalline silicon and chemical dynamics factors of the wet etching,we successfully implemented the flexibility of monocrystalline silicon materials,and made the uniform thinning monocrystalline silicon wafer with different thickness,little and uniform pyramid structures,and the composite structures with various morphologies and orientations of nanowires.The flexibility of monocrystalline silicon material and a variety of micro-nano composite structure were realized.Antireflection of the whole Angle of incident light with different structures was studied.Results indicated that the visible light reflectance of composite structure reduced from 40%to below 5%at light incident angle of 0-45°,showed excellent omnidirectional low-reflectional characteristics.2.By means of ink-jet printing technique,flexible and all-solid-state micro-supercapacitors(MSCs)were fabricated with carbon-based hybrid ink composed of graphene oxide(GO)and commercial pen ink.Due to the presence of a large number of graphite carbon nanoparticles(CNPs)served as nano-spacer to separate GO sheets,the structure stability problem was solved and the as-obtained devices exhibit nearly 780%enhancement in areal capacitance compared to that of printed devices based on pure graphene oxide ink.After the bending test of 500 times,the appearance and performance of the capacitor remain unchanged.The as-obtained devices show excellent flexibility and cycling stability,with nearly 100%retention of the areal capacitance after 10000 cycles.3.Through the distribution regulation of graphene oxide surface functional groups,a planar moisure sensor to generating electric power has been fabricated.The results show that GO sensor exhibit high humidity response sensitivity,linear humidity-voltage response in the detection range of 33-98%RH,fast response and recovery,good long term stability.By use the GO sensor,we measure the human respiration,the results show that different respiratory frequency(12-40 times/min)and respiratory pattern can be detected.For nearly 1000 times the breathing process of testing and placed after 3 months,the sensor still has good repeatability and cycle stability.An intelligent portable/wearable electrical system based on graphene oxide humidity sensor and Bluetooth wireless communication technology is designed and fabricated.The sensor system achieves functions of record of respiratory frequency,apnea alarm,real-time display of respiratory signal waveform,etc.4.Based on excellent properties of silver nanowires(AgNWs)structure,a flexible transparent heater has been fabricated,which realizing to control the heat temperature range from 40 to 100°C.After 100 cycle tests at high voltage of 28 V,the surface temperature of the heater had nearly no change.Even the heater was bent into cylindrical,it can still work normally,suggesting that heater had a wide range of temperature control,good temperature stability,fast response time,long cycle stability and flexibility.By studying the electrical breakdown failure mechanism of the heater with different square resistance,the results showed that the breakdown failure of the heater with low resistance(<50 ?/?)was mainly ascribed to the high heating temperature of the heater,resulting in thermal fuse of the silver nanowires and the heat damage failure of the basal.The failure mechanism of the heater with a high resistance(>50 ?/?)was mainly owed to the coefficient failure of electromigration and heating effect,and as the square resistance increased gradually,the proportion of the failure resulting from electromigration was more larger.