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

• Published in: Nano letters Vol. 6; no. 7; pp. 1454 - 1458
• Main Authors: Keem, Kihyun, Jeong, Dong-Young, Kim, Sangsig, Lee, Moon-Sook, Yeo, In-Seok, Chung, U-In, Moon, Joo-Tae
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-07-2006
• Subjects: Aluminum Oxide - chemistry; Cross-disciplinary physics: materials science; rheology; Equipment Design; Exact sciences and technology; Growth from vapor; Materials science; Methods of crystal growth; physics of crystal growth; Methods of nanofabrication; Microscopy, Scanning Tunneling; Nanoscale materials and structures: fabrication and characterization; Nanostructures; Other topics in nanoscale materials and structures; Physics; Quantum wires; Surface Properties; Transistors, Electronic; Zinc Oxide - chemistry; Atomic layer method; Field effect transistors; Digital simulation; Crystal growth from vapors; Nanowires; Nanostructured materials; Gates; Transconductance; Nanomaterial synthesis
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl060708x

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 Al2O3 using atomic layer deposition, which surrounds the channels and acts as a gate dielectric. About 80% of the surfaces of the nanowires coated with Al2O3 are covered with the gate metal to form OSG FETs. A representative OSG FET fabricated in this study exhibits a mobility of 30.2 cm2/ (V s), a peak transconductance of 0.4 μS (V g = −2.2 V), and an I on/I off ratio of 107. 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 106 times, respectively, compared with a back-gate FET with the same ZnO nanowire channel as utilized in the OSG FET.