Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 61: GaN: Preparation and Characterization II (mainly structural)

HL 61.4: Vortrag

Mittwoch, 28. März 2012, 15:45–16:00, EW 202

Determination of piezoelectric fields in GaN/InGaN/GaN quantum wells by DPC — •Josef Zweck¹, Matthias Lohr¹, Michael Jetter², Clemens Wächter², Thomas Wunderer³, and Ferdinand Scholz³ — ¹Physics Faculty, University of Regensburg, FRG — ²Institute for semiconductor optics and functional interfaces, Stuttgart University, FRG — ³Institute for optoelectronics, Ulm University, FRG

Differential phase contrast microscopy senses the local electric field by measuring the deflection of the probe beam after passing through a specimen area carrying an electric field.

An application of the technique to measure piezoelectric polarization fields inside multi-layered structures such as quantum wells is demonstrated. For this purpose, piezoelectric fields within non-centrosymmetric crystal structures, based on GaN/InGaN/GaN quantum wells, are investigated. It can be shown that the technique is sensitive to these fields and yields detailed and quantitative information about the field distribution. The specific information and experimental limitations will be discussed in detail and first measurements are shown.

The main advantages turn out to be high sensitivity for electric fields, combined with a very high resolution in the nanometer regime, which is only limited by the STEM probe size. Another advantage is the large achievable field of view.