Carnegie Mellon University

Randall Feenstra

Randall Feenstra

Professor, Physics




Ph.D., California Institute of Technology


The research activities of my group deal with structural and electronic properties of semiconductor materials and devices. A major tool used in the studies is the scanning tunneling microscope, which allows one to image the atomic structure of a surface and to perform spectroscopic measurements of the electronic energy levels. Many of the studies deal with semiconductor heterostructures consisting of multiple layers of different types of material, with the goal of understanding how the structure of the device (including imperfections and defects) determines its electronic properties. Growth of semiconductor heterostructures has been performed in my laboratory using molecular beam epitaxy, for GaN in particular (a semiconductor with a relatively large band gap, used for blue light-emitting devices and for microwave transistor applications).

Most recently we have focused on the study of two-dimensional (2D) materials, including graphene and hexagonal boron nitride (h-BN). We prepare these materials by growth at high temperatures, and we characterize them using both scanning tunneling microscopy and low-energy electron microscopy. The latter permits both diffraction and imaging of the surfaces, with nm-scale resolution. Additionally, spectroscopic observation of energy levels above the vacuum level is performed, which is particularly useful for these 2D materials. Heterostructures consisting of alternating layers of graphene and h-BN are being studied, because of the unique current-voltage characteristic for tunneling in such structures.

Description of research, and publications, in Prof. Feenstra's group.


  • Sergio C. de la Barrera, Randall M. Feenstra, Theory of resonant tunneling in bilayer-graphene/hexagonal-boron-nitride heterostructuresApplied Physics Letters 106, 93115 (2015)
  • Wattaka Sitaputra, Nikhil Sivadas, Marek Skowronski, Di Xiao, Randall M. Feenstra, Oxygen vacancies on SrO-terminated SrTi O3( 001 ) surfaces studied by scanning tunneling spectroscopy Physical Review B 91, 205408 (2015)
  • Kendal W. Clark, X.-G. Zhang, Gong Gu, Jewook Park, Guowei He, R. M. Feenstra, An-Ping Li, Energy Gap Induced by Friedel Oscillations Manifested as Transport Asymmetry at Monolayer-Bilayer Graphene BoundariesPhysical Review X 4, 11021 (2014)
  • N. Srivastava, Qin Gao, M. Widom, R. M. Feenstra, Shu Nie, K. F. McCarty, I. V. Vlassiouk, Low-energy electron reflectivity of graphene on copper and other substratesPhys. Rev. B 87, 245414 (2013)
  • Jewook Park, Guowei He, R. M. Feenstra, An-Ping Li, Atomic-Scale Mapping of Thermoelectric Power on Graphene: Role of Defects and BoundariesNano Lett. 13, 3269 (2013)
  • R. M. Feenstra, Debdeep Jena, Gong Gu, Single-particle tunneling in doped graphene-insulator-graphene junctionsJournal of Applied Physics 111, 43711 (2012)
  • N. Srivastava, Guowei He, Luxmi, R. M. Feenstra, Interface structure of graphene on SiC(0001̅)Physical Review B 85, 041404 (2012)
  • Luxmi, N. Srivastava, Guowei He, R. M. Feenstra, P. J. Fisher, Comparison of graphene formation on C-face and Si-face SiC {0001} surfacesPhysical Review B 82, 235406 (2010)
  • Gong Gu, Shu Nie, R. M. Feenstra, R. P. Devaty, W. J. Choyke, Winston K. Chan, Michael G. Kane, Field effect in epitaxial graphene on a silicon carbide substrateApplied Physics Letters 90, 253507 (2007)
  • C. D. Lee, Ashutosh Sagar, R. M. Feenstra, C. K. Inoki, T. S. Kuan, W. L. Sarney, L. Salamanca-Riba, Role of Ga flux in dislocation reduction in GaN films grown on SiC(0001)Applied Physics Letters 79, 3428 (2001)
  • Huajie Chen, R. Feenstra, J. Northrup, T. Zywietz, J. Neugebauer, Spontaneous Formation of Indium-Rich Nanostructures on InGaN(0001) SurfacesPhysical Review Letters 85, 1902 (2000)
  • A. R. Smith, R. M. Feenstra, D. W. Greve, M.-S. Shin, M. Skowronski, J. Neugebauer, J. E. Northrup,Determination of wurtzite GaN lattice polarity based on surface reconstructionApplied Physics Letters 72, 2114 (1998)
  • A. Smith, R. Feenstra, D. Greve, J. Neugebauer, J. Northrup, Reconstructions of the GaN(0001̅) Surface,Physical Review Letters 79, 3934 (1997)