Oral Presentation 24th Australian Conference on Microscopy and Microanalysis 2016

Differential phase contrast imaging of the electric field at a p-n junction (#15)

Scott D. Findlay 1 , Hirokazu Sasaki 2 , Takao Matsumoto 3 , Hidetaka Sawada 4 , Yuji Kohno 4 , Shinya Otomo 2 , Ryuichiro Minato 2 , Yuichi Ikuhara 3 5 , Naoya Shibata 3 6
  1. Monash University, Clayton, VIC, Australia
  2. Furukawa Electric Ltd., Yokohama, Japan
  3. Institute of Engineering Innovation, The University of Tokyo, Tokyo, Japan
  4. JEOL Ltd, Tokyo, Japan
  5. Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, Japan
  6. PRESTO, Japan Science and Technology Agency, Saitama, Japan

The properties of many modern materials and devices result from electric field structure and charge distribution at nanodimensions.  Direct observation, characterization and precise measurement of such local electric fields is a key goal in microscopy.  We discuss recent work using differential phase contrast imaging based on a segmented detector in a scanning transmission electron microscope (STEM) to image the electric field structure across a p-n junction in a GaAs compound semiconductor.1   Taking the difference between STEM images from opposing detector segments allows the built-in electric field at the junction to be clearly visualized.  Further, by calibrating simulations against experimentally-measured intensities, a model-based, quantitative estimate for the projected, built-in electric field strength at the junction is obtained.  We will discuss the validity of the approximations made and the trade-off between resolution and sensitivity to the electric field strength.  The addition of differential phase contrast to the range of established STEM imaging modes holds much promise for enabling simultaneous characterization of both composition and electromagnetic field distribution within materials and devices at nanodimensions.

This work was supported by the PRESTO and SENTAN, JST and the JSPS KAKENHI Grant number 26289234. A part of this work was supported by Grant-in-Aid for Scientific Research on Innovative Areas (25106003). A part of this work was conducted in Research Hub for Advanced Nano Characterization, The University of Tokyo, under the support of “Nanotechnology Platform” (project No.12024046) by MEXT, Japan. This research was supported under the Discovery Projects funding scheme of the Australian Research Council (Project No. DP110101570).

  1. N. Shibata, S.D. Findlay, H. Sasaki, T. Matsumoto, H. Sawada, Y. Kohno, S. Otomo, R. Minato, Y. Ikuhara, Imaging of built-in electric field at a p-n junction by scanning transmission electron microscopy, Scientific Reports 5 (2015) 10040.