Journal Article

FZJ-2024-05005

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Origin of giant enhancement of phase contrast in electron holography of modulation-doped n -type GaN

Ji, K.FZJ* ; Schnedler, M.FZJ* ; Lan, Q.FZJ* ; Carlin, J.-F. ; Butté, R. ; Grandjean, N. ; Dunin-Borkowski, R. E.FZJ* ; Ebert, P. (Corresponding author)FZJ*

2024
Elsevier Science Amsterdam

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Please use a persistent id in citations: doi:10.1016/j.ultramic.2024.114006  doi:10.34734/FZJ-2024-05005

Abstract: The electron optical phase contrast probed by electron holography at n-n+ GaN doping steps is found to exhibit a giant enhancement, in sharp contrast to the always smaller than expected phase contrast reported for p-n junctions. We unravel the physical origin of the giant enhancement by combining off-axis electron holography data with self-consistent electrostatic potential calculations. The predominant contribution to the phase contrast is shown to arise from the doping dependent screening length of the surface Fermi-level pinning, which is induced by FIB-implanted carbon point defects below the outer amorphous shell. The contribution of the built-in potential is negligible for modulation doping and only relevant for large built-in potentials at e.g. p-n junctions. This work provides a quantitative approach to so-called dead layers at TEM lamellas.

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Contributing Institute(s):

1. Physik Nanoskaliger Systeme (ER-C-1)

Research Program(s):

1. 5353 - Understanding the Structural and Functional Behavior of Solid State Systems (POF4-535) (POF4-535)
2. DFG project 398305088 - Grundlegende Eigenschaften nicht-polarer Oberflächen von ternären Gruppe-III-Nitrid-Verbindungshalbleitern (398305088) (398305088)
3. AIDAS - Joint Virtual Laboratory for AI, Data Analytics and Scalable Simulation (aidas_20200731) (aidas_20200731)

Appears in the scientific report 2024

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