Electron irradiation effect on the Schottky gate of ZnO nanowires-based field effect transistors

2011 ◽  
Vol 6 (6) ◽  
pp. 437 ◽  
Author(s):  
Qi Zhang ◽  
Junjie Qi ◽  
Yunhua Huang ◽  
Xin Li ◽  
Yue Zhang
Keyword(s):  
Electron Irradiation ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Zno Nanowires ◽  
Irradiation Effect

The effect of excimer laser annealing on ZnO nanowires and their field effect transistors

2009 ◽  
Vol 20 (9) ◽  
pp. 095203 ◽  
Author(s):  
Jongsun Maeng ◽  
Sungho Heo ◽  
Gunho Jo ◽  
Minhyeok Choe ◽  
Seonghyun Kim ◽  
...  
Keyword(s):  
Excimer Laser ◽  
Field Effect ◽  
Laser Annealing ◽  
Field Effect Transistors ◽  
Zno Nanowires ◽  
Excimer Laser Annealing

scholarly journals Effect of Electron Irradiation on the Transport and Field Emission Properties of Few-Layer MoS2 Field-Effect Transistors

2018 ◽  
Vol 123 (2) ◽  
pp. 1454-1461 ◽  
Author(s):  
Filippo Giubileo ◽  
Laura Iemmo ◽  
Maurizio Passacantando ◽  
Francesca Urban ◽  
Giuseppe Luongo ◽  
...  
Keyword(s):  
Field Emission ◽  
Electron Irradiation ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Emission Properties ◽  
Field Emission Properties

scholarly journals Laterally Grown ZnO Nanowires for Sensing Applications

2021 ◽  
Author(s):  
◽  
Campbell Matthews
Keyword(s):  
Field Dependence ◽  
Gas Sensors ◽  
Seed Layer ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Pressure Sensors ◽  
Zno Nanowires ◽  
Hydrothermal Growth ◽  
Maximum Deviation ◽  
Sensing Applications

<p>Zinc oxide nanowires are a semiconducting material that has many uses in electronic applications. In particular, ZnO nanowires have been used in field effect transistors and applied as sensors for the detection of gases, biomolecules, UV light and as pressure sensors. ZnO nanowires can be fabricated using many different methods, but most require the use of high tempertures and have extensive setup costs. Hydrothermal growth, however, provides a cheap and low temperture method for growing ZnO nanowires. Much work has been done on the synthesis and charcetristaion of ZnO nanowires grown using hydrothermal growth, in partiuclar for photovoltaic applications. Little work has been done on the performace of hydrothermally grown ZnO nanowires in field effect transtors.  This thesis looks at applying hydrothermally grown ZnO nanowires as field effect transistors (FET). The FETs are characterised and developed with the intention of using them in senseing applications. The nanowire FET structure is optimised for sensing by developing a method that constrains the nanowires to exclusively lateral growth. A Ti capping layer is fabricated on top of a ZnO seed layer. The ZnO seed layer is then etched with dilute acid so that the Ti layer overhangs the ZnO. This acts as a physical barrier to vertical wire growth from the ZnO seed layer. The maximum deviation of the nanowires from the horizontal can be controlled by etching for different times.  Two device types are fabricated using different size nanowires. One uses large nanowires, or nanorods (diameter 400 nm), while the second device type uses a hybrid structure of large nanorods with much thinner nanowires (diameter 20 nm) growing off them. Both device types are characterised as FETs in dry conditions and also when immersed in a number of different liquids. Two different gating setups are also used with the Si/SiO₂ substrate used as a backgate and a Ag/AgCl electrode inserted into liquid as a topgate.  The large nanorods only show field dependence when wet due to the large capacitance of the elctric double layer and enhanced band bending. The wet nanorods can achieve on/off ratios of 10³. In contrast, the thinner nanowires show field dependence both when dry and when wet. On/off ratios of more than 10⁴ are achieved. In general the nanowires have superior on off ratios and smaller off current due to their larger surface to volume ratio.  Attempts are made to functionalise the nanowires with aptamers so that they can be used as a biosensor. The functionalisation procedure is documented, however the overall procedure proves to be unsuccessful due to the instability and dissolution of the nanowires in tris buffer. The rate of decay in buffer solution is investigated.  Both device types are also tested as gas sensors for humidity and ethanol detection. The nanorods show no apparent detection, while the nanowires show some response to ethanol. Further development of the experimental setup is necessary to better characterise the devices.  Finally future work on these nanowires is discussed and possible improvements proposed for future development as biosensors and gas sensors.</p>

scholarly journals Electron Irradiation of Metal Contacts in Monolayer MoS2 Field-Effect Transistors

2020 ◽  
Vol 12 (36) ◽  
pp. 40532-40540 ◽  
Author(s):  
Aniello Pelella ◽  
Osamah Kharsah ◽  
Alessandro Grillo ◽  
Francesca Urban ◽  
Maurizio Passacantando ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Monolayer Mos2 ◽  
Metal Contacts

scholarly journals Laterally Grown ZnO Nanowires for Sensing Applications

2021 ◽  
Author(s):  
◽  
Campbell Matthews
Keyword(s):  
Field Dependence ◽  
Gas Sensors ◽  
Seed Layer ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Pressure Sensors ◽  
Zno Nanowires ◽  
Hydrothermal Growth ◽  
Maximum Deviation ◽  
Sensing Applications

<p>Zinc oxide nanowires are a semiconducting material that has many uses in electronic applications. In particular, ZnO nanowires have been used in field effect transistors and applied as sensors for the detection of gases, biomolecules, UV light and as pressure sensors. ZnO nanowires can be fabricated using many different methods, but most require the use of high tempertures and have extensive setup costs. Hydrothermal growth, however, provides a cheap and low temperture method for growing ZnO nanowires. Much work has been done on the synthesis and charcetristaion of ZnO nanowires grown using hydrothermal growth, in partiuclar for photovoltaic applications. Little work has been done on the performace of hydrothermally grown ZnO nanowires in field effect transtors.  This thesis looks at applying hydrothermally grown ZnO nanowires as field effect transistors (FET). The FETs are characterised and developed with the intention of using them in senseing applications. The nanowire FET structure is optimised for sensing by developing a method that constrains the nanowires to exclusively lateral growth. A Ti capping layer is fabricated on top of a ZnO seed layer. The ZnO seed layer is then etched with dilute acid so that the Ti layer overhangs the ZnO. This acts as a physical barrier to vertical wire growth from the ZnO seed layer. The maximum deviation of the nanowires from the horizontal can be controlled by etching for different times.  Two device types are fabricated using different size nanowires. One uses large nanowires, or nanorods (diameter 400 nm), while the second device type uses a hybrid structure of large nanorods with much thinner nanowires (diameter 20 nm) growing off them. Both device types are characterised as FETs in dry conditions and also when immersed in a number of different liquids. Two different gating setups are also used with the Si/SiO₂ substrate used as a backgate and a Ag/AgCl electrode inserted into liquid as a topgate.  The large nanorods only show field dependence when wet due to the large capacitance of the elctric double layer and enhanced band bending. The wet nanorods can achieve on/off ratios of 10³. In contrast, the thinner nanowires show field dependence both when dry and when wet. On/off ratios of more than 10⁴ are achieved. In general the nanowires have superior on off ratios and smaller off current due to their larger surface to volume ratio.  Attempts are made to functionalise the nanowires with aptamers so that they can be used as a biosensor. The functionalisation procedure is documented, however the overall procedure proves to be unsuccessful due to the instability and dissolution of the nanowires in tris buffer. The rate of decay in buffer solution is investigated.  Both device types are also tested as gas sensors for humidity and ethanol detection. The nanorods show no apparent detection, while the nanowires show some response to ethanol. Further development of the experimental setup is necessary to better characterise the devices.  Finally future work on these nanowires is discussed and possible improvements proposed for future development as biosensors and gas sensors.</p>

scholarly journals ZnO nanowires and their application in field-effect transistors

2021 ◽  
Author(s):  
◽  
Conor Patrick Burke-Govey
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Field Dependence ◽  
Threshold Voltage ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Zno Nanowires ◽  
High Temperature Annealing ◽  
Zno Nanowire ◽  
Threshold Voltages

<p>ZnO nanowires have shown great promise as a semiconducting material for a variety of different electronic applications at the nanoscale, and can be easily synthesised at low temperatures using the hydrothermal growth method. However, efforts to reliably produce field-effect transistors (FETs) using ZnO nanowires have been hampered by excessive charge carriers, requiring high temperature annealing (≥400°C) at the expense of the low-temperature synthesis before field dependence is achieved. This thesis presents hydrothermally synthesised ZnO nanowires which can effectively be used as FETs in dry and liquid environments without requiring any annealing or post-growth processing.  The role of polyethylenimine (PEI) in the hydrothermal growth of vertical ZnO nanowires is thoroughly investigated. PEI is a polymer used to increase the aspect ratio of ZnO nanowires, but the molecular weight of the polymer and interactions with other growth precursors are often overlooked. Using 4 mM of PEI(MW = 1300 g/mol) results in hierarchical nanowires, consisting of large primary nanowires which abruptly terminate in thinner secondary nanowires. The secondary nanowires, with lengths of up to 10 m and diameters below 50 nm, are synthesised during a PEI-mediated secondary growth phase, where Zn-PEI complexes continue to provide Zn²⁺ ions after the bulk of the precursors have been exhausted.  The PEI-mediated synthesis of hierarchical nanowires is used to fabricate FETs by laterally growing intersecting networks of nanowires from spaced pairs of ZnO/Ti films, which have been patterned on SiO₂/Si device substrates. All of these FETs show marked field dependence between VG = -10 V to 10 V, despite being used without annealing. Typical on-off ratios are between 10³ - 10⁵, with threshold voltages between -7.5 V to 5 V. This is a significant result, as the majority of ZnO nanowire FETs reported in the literature require high temperature annealing. Persistent photoconductivity measurements indicate that surface states on the nanowires contribute to the intrinsic field dependence of the devices.  Hierarchical nanowires are also synthesised by modular primary and secondary hydrothermal growths. FETs fabricated using these hierarchical nanowires show less field dependence than PEI-mediated hierarchical nanowires, with limited function ality when used in air. The best FET measured in air operates with an on-off ratio of 10⁴ and a threshold voltage of ~ 0 V. Devices which are field-independent in air can be reliably gated by measuring the FETs in a wet environment, using de-ionised water as a dielectric. A back-gated wet FET operates with an on-off ratio of 105 and a threshold voltage of ~ 8 V. Top-gated wet FETs operate with on-off ratios within 103 - 104, and threshold voltages within 0.4 - 0.9 V. These devices also have significantly low subthreshold swings, on the order of 80 mV/decade.  FETs are fabricated by contacting individual ZnO nanowires using electron-beam lithography, although only one vertical ZnO nanowire shows field dependence, with an on-off ratio of 10⁴ and a threshold voltage of -7 V. A PEI-mediated hierarchical nanowire is also contacted and shows field dependence, with an on-off ratio of 10² and a threshold voltage of -6 V. The poor on-off ratio is caused by high leakage currents of the device. The contacted nanowires undergo dissolution over time, disappearing from the substrates after 8 months, and also exhibit a conducting-to-insulating transition over 48 hours. This transition can be temporarily reversed by exposure to an electron beam. Neither of these effects are reported in the literature, and their causes are speculated on.  Finally, the thesis concludes with proposals for future work to further the advances made here.</p>

Fabrication of field-effect transistors and functional nanogenerators using hydrothermally grown ZnO nanowires

RSC Advances ◽  
2015 ◽  
Vol 5 (86) ◽  
pp. 69925-69931 ◽  
Author(s):  
C. Opoku ◽  
A. S. Dahiya ◽  
F. Cayrel ◽  
G. Poulin-Vittrant ◽  
D. Alquier ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Hydrothermal Process ◽  
Zno Nanowires ◽  
Zno Nanowire ◽  
Single Crystalline ◽  
Piezoelectric Nanogenerators

We demonstrate single crystalline ZnO nanowire (NW) production using hydrothermal process. Single NW field-effect transistors (FETs) and functional piezoelectric nanogenerators (NGs) are demonstrated by thermal annealing of the NWs in air at ~450 °C.

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