AVS 64th International Symposium & Exhibition
    Advanced Ion Microscopy Focus Topic Thursday Sessions
       Session HI+BI+NS+TR-ThM

Paper HI+BI+NS+TR-ThM6
Ion Beam Induced Current Measurements of Solar Cells with Helium Ion Microscopy

Thursday, November 2, 2017, 9:40 am, Room 7 & 8

Session: Advanced Ion Microscopy Applications
Presenter: Ryan Cannon, Oak Ridge National Laboratory
Authors: A. Belianinov, Oak Ridge National Laboratory
S. Kim, Oak Ridge National Laboratory
R. Cannon, Oak Ridge National Laboratory
M.J. Burch, Oak Ridge National Laboratory
S. Jesse, Oak Ridge National Laboratory
O.S. Ovchinnikova, Oak Ridge National Laboratory
Correspondent: Click to Email
The scanning electron microscope (SEM) is a versatile high-resolution microscopy tool, and perhaps the most widely used imaging platform across many engineering and scientific fields [1]. Within the last decade, another microscopy technique based on a gaseous field ionization source, utilizing Helium and Neon ions has been introduced [2]. While the popularity of the SEM is hardly challenged by the Helium Ion Microscopy (HIM), there are instances when imaging with ions offers significant advantage as opposed to imaging with electrons. In principle, both HIM and the SEM share many similarities, for example, a HIM operating at 40 keV will generate ions with velocity comparable to SEM operating at 5 keV. However, due to much higher stopping power of ions, as compared to electrons, ion based secondary electron (iSE) will be higher. Also, as a result, there is little ion backscattering, and consequently, the concentration of the ion-generated iSE2 (additional secondary electron generated by SE interaction within the material) is usually insignificant.

In this work, we exploit small interaction volumes in the HIM, and take advantage of the lower iSE2 yield, and positively charged helium ions to map ion beam induced current (IBIC) in solar cell materials. Similar studies, using electrons, have visualized induced current profiles at grain profiles in polycrystalline solar cells, and in silicon [3, 4]. Furthermore, broad ion sources have been utilized in conjunction with scanning probe systems in the past to map out current changes in FinFETs [5]. We are interested in utilizing the HIM to map current at the nanoscale near p-n junctions in CdTe to elucidate differences in contrast captured by the ion beam induced current, as opposed to the electron beam induced current. These findings will illustrate the peculiarities of ionic transport in these solar cell materials, and will evaluate the HIM technology as a potential quality control tool.

References:

[1] David C Joy, Helium Ion Microscopy: Principles and Applications, First ed. Springer, New York USA, Heidelberg Germany, Dordrecht Netherlands, London United Kingdom, 2013.

[2] Gölzhäuser, A. and Hlawacek, G., Helium Ion Microscopy. Springer International Publishing. 2016

[3] Donolato, C., Journal of Applied Physics, 54 (3), 1314-1322, 1983

[4] Chen, J., et. al., Journal of Applied Physics, 96(10), 5490-5495, 2004

[5] Manfredotti, C., et.al., Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 380(1-2), 136-140, 1996