This study presents a method for growing and characterizing isolated and coalesced
ZnO
nanorods on a
SiO
2
/p-Si
substrate using the chemical bath deposition (CBD) technique. Characterizations of the ...nanorods were investigated using an X-ray diffractometer (XRD), atomic force microscopy (AFM), photoluminescence spectrofluorometer, and I–V parameter analyzer. The growth of
ZnO
nanorods significantly impacts the coalesced surface morphology and quantitative structural parameters. Potentiality of the
ZnO
nanorods based thin film transistor (TFT) as
NH
3
gas sensor has been explored. Experimental findings of the fabricated device structure were found to be well in agreement with the similar prototype structure simulated in TCAD environment. Maximum drain currents deviation between simulation and experimental study were found to be negligibly ± 0.2%. The
ZnO
nanorods-based TFT exhibits excellent room temperature sensitivity of ~ 226% at 50 ppm
NH
3
with threshold voltage shift towards lower
V
GS
(from 9 V in air to 6 V in 50 ppm
NH
3
)
.
The fast response (14 s) and recovery (4 s) characteristics of the TFT sensor proved to be potentiality towards ammonia leakage detection and making it highly useful for industrial safety applications. The room temperature nanorods ammonia sensing mechanism were correlated through band bending at the grain boundaries interfaces following neck-controlled depletion model.
This article investigates the performance of a vertically grown GaSb/Si tunnel field effect transistor (V-TFET) with a source pocket to enhance the performance of the device. The commercially ...available Silvaco TCAD has been used for simulating the proposed V-TFET structure. A low bandgap material, GaSb, is used in the source region for the first time to enhance the carrier tunneling through the source (GaSb)-channel (Si) heterojunction. The proposed V-TFET with a pocket shows the improved subthreshold swing (SS) of 26 mV/decade at V DS = 0.5 V over the V-TFET without any pocket. The effects of temperature on SS and I ON /I OFF ratio along with the analog/RF figures of merit (FOMs) are also analyzed for V-TFETs with and without a pocket. The results are also compared with some recently reported TFETs. The dc and analog/RF performances of V-TFET with a pocket are shown to be better than those of the V-TFET without a pocket and other reported TFET structures. Finally, the applications of V-TFETs with and without a pocket in designing inverter and ring oscillator circuits have been demonstrated. The dc and transient responses of the V-FET-based inverter and ring oscillator circuits have been analyzed using the Verilog-A model in the CADENCE tool.
In this work, multifunctional CuO nanowires (NWs) electrode-based extended-gate (EG) field-effect transistor (FET) has been explored for both pH and glucose sensing applications. The CuO nanowires ...(NWs) electrode-based EGFET gives good pH sensitivity (~48.34 mV/pH), high linearity (99.84%), good stability for pH level in between 2 and 12 for 12 hours with a drift rate of 2.5mV/h, and good reversibility in terms of low hysteresis loss of 2.5mV. The selectivity of this pH sensor towards hydrogen ion is significantly higher as compared to Na + , K + , Zn ++ and Mg ++ ions. In addition to the pH sensing, CuO NWs based electrode-based EGFET has also been explored for glucose-sensing for the first time without taking the help of neither any enzyme nor any organic receptor. The proposed glucose sensor gives a good sensitivity of 3.03 mV/mM with a high range of linearity (1mM-12mM), which covers up the glucose level of human blood ranging from 3.6 mM to 6.6 mM. This novel concept of CuO NWs based EG-FET glucose sensing is believed to be extended for sensing other saccharides such as fructose, sucrose, and mannose.
This paper reports the TCAD based investigation of the DC/RF and linearity characteristics of a newly proposed dual-material (DM) laterally-stacked (LS) SiO
2
/HfO
2
heterojunction-TFET-on-SELBOX ...substrate (LS-STFET). Device-level performance comparison is made between the proposed TFET with a dual-material (DM) vertically-stacked (VS) SiO
2
/HfO
2
heterojunction-TFET-on-SELBOX substrate (VS-STFET). Low bandgap material Ge is used in the source region to form a Ge (source)/Si (channel) heterojunction for enhancing the ON-state current of the presented TFETs. The effects of both donor (+ ve) and acceptor (−ve) type interface trap charges at the channel/SiO
2
region on the DC, analogue/RF and linearity figure of merits have been analyzed for both the devices under study. The LS-STFET is shown to possess higher ON-state current and smaller subthreshold swing (SS) over the VS-STFET. In addition, the LS-STFET is shown to have better DC, analog/RF and linearity performance over VS-STFET in the presence of the donor and acceptor interface trap charges.
This paper explores gold nanoparticle (GNP) modified copper oxide nanowires(CuO NWs)based electrode grown on copper foil for non-enzymatic glucose detection in a wide linear ranging up to 31.06 mM, ...and 44.36 mM at 0.5 M NaOH and 1 M NaOH concentrations. The proposed electrode can be used to detect a very low glucose concentration of 0.3 µM with a high linearity range of 44.36mM and sensitivity of 1591.44 µA mM
cm
. The electrode is fabricated by first synthesizing Cu (OH)
NWs on a copper foil by chemical etching method and then heat treatment is performed to convert Cu (OH)
NWs into CuO NWs. The GNPs are deposited on CuO NWs to enhance the effective surface-to-volume ratio of the electrode with improved catalytic activity. The surface morphology has been investigated by XRD, XPS, FE-SEM and HR-TEM analysis. The proposed sensor is expected to detect low-level of glucose in urine, and saliva. At the same time, it can also be used to measure extremely high sugar levels (i.e. hyperglycemia) of ~ 806.5454 mg/dl. The proposed sensor is also capable of detecting glucose after multiple bending of the GNP modified CuO NWs electrode. The proposed device is also used to detect the blood sugar level in human being and it is found that this sensor's result is highly accurate and reliable.
This letter reports a SnS2 and ZnO nanocomposite (NC) prepared by dispersion method. The nanocomposite shows promising characteristics for optoelectronic application. SnS2:ZnO NC shows a wide ...absorption spectrum covering ultraviolet (UV)-visible-near infrared (NIR) regions. Hence, using the proposed nanocomposite a broadband photodetector with a structure comprising Al/ SnS2:ZnO/PEDOT:PSS/ Indium Tin Oxide (ITO) is fabricated. At a bias voltage of 1 V, the measured responsivity values (A/W) of the proposed device are 140.41, 848.63, and 1094.48 at 350 nm (UV), 750 nm (visible) and 900 nm (NIR), respectively.
The electrical and ammonia gas sensing properties of poly (3, 3"'-dialkylquaterthiophene) (i.e., PQT-12) and CdSe quantum dots (QDs) composite-based back-gated organic thin film transistors (OTFTs) ...fabricated on SiO 2 coated heavily doped p-Si substrates by solution method have been investigated in this paper. The properties of pristine PQT-12 and PQT-12/CdSe QDs composite films have been investigated by transmission electron microscopy and atomic force microscopy. To investigate the effect of colloidal CdSe QDs on the characteristics of PQT-12-based OTFTs, the performance of pristine PQT-12-based OTFT has been compared with that of the PQT-12/CdSe QDs composite-based OTFT. The field effect mobility, threshold voltage, on/off current ratio, and subthreshold swing of the PQT-12/CdSe QDs composite-based OTFT are 4.2×10 -3 cm 2 /Vs, -14.4 V, 1.9×10 3 , and 5.2 V/dec while the corresponding values for pristine PQT-12-based OTFT are 1.4× 10 -3 cm 2 /Vs, -22.1 V, 3.6× 10 2 , and 7.9 V/dec, respectively. When the devices are exposed to ammonia gas, an estimated gas response of ~51% is obtained for PQT-12/CdSe QDs composite-based OTFT whereas the gas response of ~41% is achieved for the pristine PQT-12 OTFT sensor. The improved gas response in the PQT-12/CdSe QDs composite-based OTFT is attributed to enhanced charge transfer due to the CdSe QDs as compared with the pristine PQT-12-based OTFT.
The effects of stacked SiO
2
/HfO
2
gate oxide, source pocket, and underlap gate engineering on the electrical and RF performances of cylindrical gate tunnel field-effect transistors (CGTFETs) have ...been investigated in this paper. While source pocket with underlap engineering reduces both the gate leakage current and subthreshold swing (SS), the stacked gate oxide improves the drain current of the CGTFET. The DC and RF performance parameters such as the electric field, drain current, transconductance, gate capacitance, unity gain cut-off frequency, gain–bandwidth product, transconductance frequency product, and intrinsic delay have been investigated for different stacked oxide CGTFETs with and without a source pocket as well as with and without an underlap structure. Our study demonstrates that the proposed underlapped stacked-oxide source-pocket engineered CGTFET structure not only enhances the drain current, but also improves the subthreshold switching characteristics of the device by reducing SS and gate leakage current.
Atomic arrangements in the nanostructured grains and interfaces of thermally evaporated Au/Cu multilayer thin films on polycrystalline Si substrate have been explored through GIXRD, HRTEM, ...simulation, and direct structure imaging. GIXRD pattern conforms to cF4 solid solution of Au and Cu with peak broadening and shift. Comparative analysis with simulation indicated the presence of cP4, tP4, oP8, and oI40 phases in the multilayer. The Cu layer is amorphous. Localized amorphous phase forms at the Cu–Si interface due to the impingement of Cu atoms during deposition. Interfaces of Au–Cu are wavy. The Au layer is polycrystalline and columnar with some twin-like defects present in them. At the Cu–Au interface, diffusionally grown cP4, tP4, oI40, and oP8 phases could be observed. Adatom mobility, concurrent growth, and coalescence of growth islands lead to columnar growth. Ordered intermetallic phases could be related with the cF4 solid solution phase through polymorphism. The strain associated with the polymorphs and the solid solution phase is quite small. Faceted semi-coherent interfaces of the ordered phases with the solid solution phase have been resolved. The ordered phases grow into the solid solution matrix by homogeneous transformation. Structure imaging of the ordered phases indicated that most of the time a cluster of atoms is imaged in these structures. The interfaces are likely to be chemically diffused in nature. Polymorphism and homogeneous nature of the transformation at low temperature allows local transformation to ordered phases, that explain the phase field ambiguity in the binary phase diagram. Such structural details are critical in understanding the novel properties in these nanostructured alloys.
Graphical abstract
In this study, we have developed a wireless, portable, standalone, and simple electric cell-substrate impedance sensing (ECIS) system to analyze in-depth functional aspects of cellular functions on ...the surface of a co-planar metal electrode coated on conventional glass substrate using a low-cost circuitry and correlated it with an equivalent electrical circuit (EEC) model. Low-cost circuitry was used for studying the dynamic behavior of the mouse myoblast cells (C2C12) in a culture chamber. Further, the developed ECIS system was connected with 8-bit Arduino UNO microcontroller board for establishing a compact sized measuring unit, which can be placed inside a CO
2
incubator to provide proper environmental condition for the biological cells during the entire measuring time. Integrating ZigBee RF module with the 8-bit Arduino UNO microcontroller board provides a wireless communication network. Theoretical calculation of the lumped-elemental electrical parameters associated with cell-electrolyte interface and metal-electrolyte interface was calculated. The calculation was performed by fitting the experimental impedance data to EEC model using least mean square method to determine the dynamic and vital functions of the mammalian cells such as proliferation (in real-time) with a change in intrinsic electrical parameters associated at any particular time point. Impedance measurements and the lumped-elemental electrical parameter were correlated with the respective microscopic images. The developed ECIS system was found to enable measuring of the extent of cellular proliferation over time. The compactness of the developed ECIS system integrated with the ZigBee RF module and the 8-bit Arduino UNO microcontroller board facilitates its utilization even when placed in the CO
2
incubator for a prolonged time.
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