Fabrication and Device Characterization of Omega-Shaped-Gate ZnO Nanowire Field-Effect Transistors

Abstract

Omega-shaped-gate (OSG) nanowire-based field effect transistors (FETs) have attracted a great deal of attention recently, because theoretical simulations predicted that they should have a higher device performance than nanowire-based FETs with other gate geometries. OSG FETs with channels composed of ZnO nanowires were successfully fabricated in this study using photolithographic processes. In the OSG FETs fabricated on oxidized Si substrates, the channels composed of ZnO nanowires with diameters of about 110 nm are coated with Al(2)O(3) using atomic layer deposition, which surrounds the channels and acts as a gate dielectric. About 80% of the surfaces of the nanowires coated with Al(2)O(3) are covered with the gate metal to form OSG FETs. A representative OSG FET fabricated in this study exhibits a mobility of 30.2 cm(2)/ (V s), a peak transconductance of 0.4 muS (V(g) = -2.2 V), and an I(on)/I(off) ratio of 10(7). To the best of our knowledge, the value of the I(on)/I(off) ratio obtained from this OSG FET is higher than that of any of the previously reported nanowire-based FETs. Its mobility, peak transconductance, and I(on)/I(off) ratio are remarkably enhanced by 3.5, 32, and 10(6) times, respectively, compared with a back-gate FET with the same ZnO nanowire channel as utilized in the OSG FET.

Synthesis of ZnO nanostructures composed of nanosheets with controllable morphologies

“…Znic oxide (ZnO), an important semiconducting oxide with a direct wide band gap (3.37 eV) and large excitation binding energy (60 meV) at room temperature, is a promising material for lighting emission, gas sensors, and solar cells. Recently, much attention has been paid to the synthesis of ZnO nanostructures, such as nanorods [2][3][4][5], nanowires [6,7], nanotubes [8][9][10], nanobelts [11], nanorings [12], nanohelices [13], nanosheets [14][15][16], nanoplatelets [17], and hollow spheres [18], due to their specific optical properties [19] and potential applications in piezoelectric nanogenerators [20], ultraviolet nanolasers [21,22], dye-sensitized solar cells [14,23], broad light-emitting diode [24], field-effect transistors [25], reverse superhydrophobicity to super-hydrophilicity transition [26], and photocatalysts [17]. A variety of methods such as thermal evaporation [11][12][13], chemical vapor deposition [27], electrodeposition [28], biomimetic synthesis [6], hydrothermal synthesis [29,30], low temperature solution-phase synthesis [5,31], and template-based synthesis [8], have been developed to fabricate ZnO nanostructures.…”

Tunable n‐Type Conductivity and Transport Properties of Ga‐doped ZnO Nanowire Arrays

“…In addition, the electron mobility (l) can be estimated from the channel conductance (g m ) of FET. In the linear regime (V g from -40 to 15 V), [27,34,[38][39] The I DS versus V g plot in semi-logarithmic scale at a constant V DS =1 V is plotted in the lower inset of Figure 4a, which shows clearly a threshold voltage about -40V and an on/off ratio as large as 10…”

DC-field-induced synthesis of ZnO nanowhiskers in water-in-oil microemulsions

“…It also has superior photoelectronic properties. One-dimensional ZnO nanomaterials are widely used in fabricating piezoelectric nanogenerators [4], photodiodes [5], varistors [6], light-emitting diodes [7], displays [8,9], field effect transistors [10][11][12], solar cells [13], sensors [14][15][16][17][18], etc. ZnO crystal whiskers with high aspect ratio have been used as reinforced composite materials [19] and probing tips in atomic force microscopy and scanning tunneling microscopy [20].…”