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Dopant-free GaN/AlN/AlGaN radial nanowire heterostructures as high electron mobility transistors

Li, Yat and Xiang, Jie and Qian, Fang and Gradecak, Silvija and Wu, Yue and Yan, Hao and Yan, Hao and Blom, Douglas A. and Lieber, Charles M. (2006) Dopant-free GaN/AlN/AlGaN radial nanowire heterostructures as high electron mobility transistors. NANO LETTERS, 6 (7). pp. 1468-1473.

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We report the rational synthesis of dopant-free GaN/AlN/AlGaN radial nanowire heterostructures and their implementation as high electron mobility transistors (HEMTs). The radial nanowire heterostructures were prepared by sequential shell growth immediately following nanowire elongation using metal-organic chemical vapor deposition (MOCVD). Transmission electron microscopy (TEM) studies reveal that the GaN/AlN/AlGaN radial nanowire heterostructures are dislocation-free single crystals. In addition, the thicknesses and compositions of the individual AlN and AlGaN shells were unambiguously identified using cross-sectional high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM). Transport measurements carried out on GaN/AlN/AlGaN and GaN nanowires prepared using similar conditions demonstrate the existence of electron gas in the undoped GaN/AlN/AlGaN nanowire heterostructures and also yield an intrinsic electron mobility of 3100 cm(2)/Vs and 21 000 cm(2)/Vs at room temperature and 5 K, respectively, for the heterostructure. Field-effect transistors fabricated with ZrO2 dielectrics and metal top gates showed excellent gate coupling with near ideal subthreshold slopes of 68 mV/dec, an on/off current ratio of 107, and scaled on-current and transconductance values of 500 mA/mm and 420 mS/mm. The ability to control synthetically the electronic properties of nanowires using band structure design in III-nitride radial nanowire heterostructures opens up new opportunities for nanoelectronics and provides a new platform to study the physics of low-dimensional electron gases.

Item Type:Article
Subjects:Physical Science > Nanoelectronics
ID Code:2774
Deposited By:Lesley Tobin
Deposited On:08 Jan 2009 16:41
Last Modified:08 Jan 2009 16:41

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