Accelerator Test Facility and Synchrotron Radiation Source at KIT

Surface electronic and chemical properties of as grown and adsorbate-covered polar and nonpolar InN

  • Date:15.10.2014
  • Speaker:Anja Eisenhardt
  • Time:14.00 p.m.
  • Abstract:

    The surface electronic properties are key parameters for the design of nitride based transistor or  sensor  devices.  For  Indium  Nitride  (InN),  a  promising  material  for  electronic  and optoelectronic  applications,  device  realization  is  very  challenging  particularly  due  to  a commonly formed strong electron accumulation layer at the InN surface and its interfaces to other materials. Understanding the intrinsic surface properties that lead to the formation of the accumulation layer might open new approaches to avoid or modify and control the surface electron concentration. 
    In  this  talk  I  will  present  investigations  of  the  surface  electronic  and  chemical  properties, measured by in-situ photoelectron spectroscopy (UPS, XPS), of polar and nonpolar oriented InN thin films prepared by plasma-assisted molecular beam epitaxy. Thereby I will show, that the surface band alignment and the formation of the electron accumulation layer are correlated with the energetic position of occupied electron states, which are different for different InN surface  configurations.  Furthermore,  I  will  present  experiments  that  reveal  that  the  surface properties  are  significantly  modified  by  adsorbates  as  characterised  by  surface  exposure  to oxygen, water, hydrogen and ammonia.

  • Affiliation:Institut  für  Physik  and  Institut  für  Mikro-  und  Nanotechnologien,  Technische  Universität Ilmenau, Germany