The role of tin oxide surface defects in determining nanonet FET response to humidity and photoexcitation

Abstract

There has been a growing interest in 1-D metal oxide semiconducting nanostructures due to their stable chemical properties and potential applications in large-area, low-cost and flexible substrates. In this current work, we used field effect transistors (FETs) built on sub-millimetre scale metal oxide nanonet to characterize the nanowire surface properties. Two variations of SnO 2 nanowires, denoted as 0% O 2 and 0.5% O 2 -Ar, were grown by changing the O 2 concentration in the growth atmosphere. HR-TEM images exhibit two dissimilar surface morphologies which represent diverse surface-defect levels. While the devices showed very little semiconducting behaviour in humid air, the flow in the dry air decreased the density of free carriers dramatically. Both water vapour and oxygen were observed to contribute to the hysteresis of transfer curves. Under white light illumination, 0% O 2 nanonet devices exhibited a significant photocurrent response in the controlled environment while almost no changes were observed for 0.5% O 2 ones. These results confirmed the significant role of surface defects in metal-oxide nanowires and implied great potential for SnO 2 nanonet FETs in the application of water gas sensors and photodetectors.

Humidity Sensor Based on Two-Dimensional SnSe2/MWCNT Nanohybrids for the Online Monitoring of Human Respiration and a Touchless Positioning Interface

“…The defect states produced near the Fermi level, called deep level defect states, can trap the charge carriers. This can significantly affect the amount of current in the resistive sensor at the high humidity level …”

“…This can significantly affect the amount of current in the resistive sensor at the high humidity level. 7 By knowing the excellent humidity responsiveness, the SnSe 2 /MWCNT nanohybrid-based humidity sensor was exploited for its application in the touchless positioning interface and real time monitoring of human respiration. Figure 4(d) shows that the current can be changed upto 63% on approaching the fingertip toward the sensor to a distance of 3 mm.…”

“…Recently, humidity sensors have captivated tremendous attention of researchers due to their advance uses in environmental control, defense, agriculture sciences, and several biomedical processes. − These applications demand highly sensitive moisture sensing and controlling techniques. Humidity responsive electronics based on various transduction techniques, such as capacitance, resistance, optical fiber, and field effect transistors (FETs), have been developed, since long. − Among them, resistive humidity sensors are the most desirable due to their low fabrication cost, fast implementation, and low power consumption . High-performance humidity sensors to create a human–machine interface should have high sensitivity, fast response, and recovery actions that can be produced by using suitable materials with optimized structural, physical, and chemical properties.…”

Controlled hybridization of Sn–SnO2 nanoparticles via simple-programmed microfluidic processes for tunable ultraviolet and blue emissions

“…[1][2][3][4][5] Among them, tin oxide (SnO 2 ) is extremely promising as an intrinsic n-type oxide semiconductor with good chemical and mechanical stability, 6 a wide bandgap of 3.6 eV at 300 K, 6 a highly achievable carrier concentration up to 6 Â 10 20 per cm 3 , 7 and an exciton-binding energy of 130 meV larger than those of ZnO (60 meV) and GaN (25 meV). 8,9 SnO 2 nanostructures have shown potential use in sensors, 10,11 transistors, [12][13][14] light-emitting diodes, 15,16 photovoltaic cells, 17 photocatalysis 18 and lithium batteries. [19][20][21] However, the even-parity symmetry of the conduction-band minimum and valence-band maximum states in SnO 2 prohibits the band-edge radiative transition and light emission, 22 which hinders their further application in optoelectronic devices, such as ultraviolet (UV) light emitters.…”

Ultrasensitive Physical, Bio, and Chemical Sensors Derived from 1‐, 2‐, and 3‐D Nanocellulosic Materials

“…Humidity sensors are important to many applications, including human life and industrial/medical/ecological monitoring, and they are generally made from metal oxides, polymers, ceramics, carbon nanomaterials, and their composites 90. Different transduction techniques are employed to develop humidity sensors, such as capacitive,91 resistive,92 optical fiber,93 field effect transistor (FET),94 surface acoustic wave (SAW),95 and quartz crystal microbalance (QCM) 96. Sensitivity is critical for humidity sensors, and various sensing materials including carbon nanomaterials, nanosized metal oxides, and metal nanowires have been studied to construct humidity sensors; and these nanostructured materials are believed to enhance the sensitivity of humidity sensors due to their large surface‐to‐volume ratio and special properties resulting from nanoscale size 90a,97.…”