Patternable production of SrTiO_(3) nanoparticles using 1-W laser directly on flexible humidity sensor platform based on ITO/SrTiO_(3)/CNT

Perovskite oxides like S rTiO_(3) at the nanoscale are of interest for eme rging applications,including high-k dielectrics and sensors.However,their synthesis requires long calcination at the elevated temperature,which is a barrier of their application to flexible electronics.Here,an effective laser-assisted sol-gel method to patternably produce S rTiO_(3) na noparticles(-100 nm)in selective areas on polyimide substrates(coated with ITO)is introduced.Importantly,the violet-laser power is just 1 W but sufficient to crystallize the material in a short period(a few seconds).Furthermore,developing a flexible device platform using carbon nanotubes(CNT)and SrTiO_(3) nanoparticles for detection of humidity changes at room temperature is proposed.The sensor platform has both capacitive and resistive sensing abilities.The resistive mode with a lower power usage(about 0.2μW)is suitable for long monitoring of humidity in the range of2%RH and above.The capacitive mode with higher sensitivity,faster response/recovery time(1-3 min),and lower detection limit(0.5%RH)can be used for calibration purposes.The performance of the flexible sensor is still maintained after 5000 bending cycles at 1.5-cm radius.Altogether,our synthesis method and the flexible sensor show chances for mass-producing perovskite oxides at low cost for wearable electronics.

Aluminum doping for optimization of ultrathin and high-k dielectric layer based on SrTiO3

An ultrathin SrTiO3 dielectric layer is optimized through Al doping to solve the problems existing in development of ultra-high-k oxide MOS capacitors.Through post-deposition annealing,Al doping induces changes in the electronic structure of SrTiO3,thereby effectively reducing leakage current to <10^-8 A/cm^2 at 0.5 MV/cm but maintains good capacitance values(ε> 80) of ultrathin SrTMO3 MOS capacitors.Strontium titanate(SrTiO3) is a high-k material but its bandgap is smaller than that of other oxide dielectrics(e.g.,SiO2,Al2 O3).Consequently,an ultrathin SrTiO3 film may have a high tunneling leakage current,which is not suitable for capacitor-based applications.To improve the performance of metal-oxide-semiconductor(MOS) capacitors using SrTiO3,an approach based on homogenous and uniform aluminum doping to SrTiO3 through co-sputtering is introduced.The bandgap of a pristine SrTiO3 film showed an increase of 0.5 eV after Al doping.Furthermore,Al doping decreased the leakage current of SrTiO3/Si-based MOS capacitors by more than five orders of magnitude(at the level of nanoampere per square centimeter).Importantly,a dielectric constant of 81.3 and equivalent oxide thickness less than 5 A were achieved in an 8-nm-thick Al-doped SrTiO3 film owing to changes in its crystal structure and conduction band edge electronic structure.Thus,the obtained data show the effectiveness of the proposed approach for solving the problems existing in the development of ultra-high-k oxide MOS capacitors.