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

Abstract

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 ZrO(2) dielectrics and metal top gates showed excellent gate coupling with near ideal subthreshold slopes of 68 mV/dec, an on/off current ratio of 10(7), 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.

• Authors: Yat Li, Jie Xiang, Fang Qian, Silvija Gradecak, Yue Wu, Hao Yan, Douglas A Blom, Charles M Lieber
• Journal: Nano letters (Nano Lett) Vol. 6 Issue 7 Pg. 1468-73 (Jul 2006) ISSN: 1530-6984 [Print] United States
• PMID: 16834431 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Aluminum Compounds
• Macromolecular Substances
• aluminum gallium nitride
• gallium nitride
• aluminum nitride
• Gallium

Topics

• Aluminum Compounds (chemistry)
• Electrons
• Gallium (chemistry)
• Macromolecular Substances
• Microscopy, Electron, Transmission
• Nanostructures
• Transistors, Electronic