Local electronic properties of AlGaNGaN heterostructures.pdfVIP

To appear in Journal of Electronic Materials (Special Issue on “III-V Nitrides and SiC” March 2000) Local electronic properties of AlGaN/GaN heterostructures probed by scanning capacitance microscopy K. V. Smith and E. T. Yu Department of Electrical and Computer Engineering University of California, San Diego La Jolla, CA 92093-0407 J. M. Redwing and K. S. Boutros ATMI/Epitronics 21002 North 19th Avenue, Suite 5 Phoenix, AZ 85027-2726 Abstract Local electronic properties in Alx Ga1-xN/GaN heterostructure field-effect transistor epitaxial layer structures are probed using scanning capacitance microscopy. Acquisition of scanning capacitance images over a wide range of bias voltages combined with theoretical analysis and numerical simulation allows the presence, detailed nature, and possible structural origins of nanometer- to micron-scale inhomogeneities in electronic structure to be elucidated. Substantial lateral variations in local threshold voltages for transistor channel formation are observed, at length scales ranging from submicron to 2µm, and found to arise primarily from local variations in Alx Ga1-xN layer thickness. Features in electronic structure are also observed that are consistent with the existence of networks of negatively charged threading edge dislocations, as might be formed a