Influence of back-scattered electrons on EBIC measurements through conductive probes

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Poster Session Three
Ing. Jakub Pongrácz (1, 3), Ing. Radek Dao (2), Prof. Roman Gröger (1)
1. Institute of Physics of Materials, Czech Academy of Sciences
2. NenoVision, s.r.o.
3. Central European Institute of Technology (CEITEC), Brno University of Technology

atomic force microscopy, electron microscopy, EBIC, correlative measurement

Abstract text

The next-generation micro-display technologies require the development of efficient miniaturized blue, green, and red light-emitting diodes (LEDs). Moreover, with the focus on creating smaller and smaller architectures for chip manufacturing, there is a growing need for more precise characterizations of conductive paths and recombination activities of individual defects. They are often made by measuring the Electron Beam Induced Current (EBIC) or the Electron Beam Absorbed Current (EBAC), both of which require the creation of a metal-semiconductor (Schottky) contact. An interesting alternative is to make the Schottky contact only locally between the semiconductor surface and a sharp conductive atomic force microscope (AFM) tip [1]. 

The main objective of this work is to adapt this technique for the near-field (high-resolution) EBIC measurements using the SPM LiteScope operated inside the chamber of SEM TESCAN Lyra-3 that serves as a source of the electron beam. It allows for simultaneous collection of the SEM signal, surface topography (AFM), and the EBIC (EBAC) signal while keeping a fixed distance between the electron source and conductive probe. No special surface treatment is needed here since the Schottky contact is created automatically when the AFM tip approaches the semiconductor surface. We use the Pt-coated Bruker AFM probe OSCM-Pt R3 connected via probe holder to the SPM LiteScope that processes the measurements. We demonstrate that the measured EBIC signal contains a significant contribution from back-scattered electrons (BSE) whose effect needs to be eliminated for high-resolution measurements. We propose ways to divert the back-scattered electrons before their absorption by the conductive probe. The standard and near-field EBIC measurements are demonstrated on samples of 200 nm AlN/Si(111) grown by MOCVD.


[1] K. Smaali, M. Troyon, Application of nano-EBIC to the characterization of GaAs and InP homojunction, Nanotechnology 19 (2008) 155706.