Chemical exfoliation and optical characterization of threading-dislocation-free gallium-nitride ultrathin nanomembranes

Rami T. ElAfandy; Mohammed A. Majid; Tien Khee Ng; Lan Zhao; Dongkyu Cha; Boon S. Ooi

doi:10.1117/12.2071471

13 November 2014 Chemical exfoliation and optical characterization of threading-dislocation-free gallium-nitride ultrathin nanomembranes

Rami T. ElAfandy, Mohammed A. Majid, Tien Khee Ng, Lan Zhao, Dongkyu Cha, Boon S. Ooi

Author Affiliations +

Proceedings Volume 9277, Nanophotonics and Micro/Nano Optics II; 927719 (2014) https://doi.org/10.1117/12.2071471
Event: SPIE/COS Photonics Asia, 2014, Beijing, China

Abstract

Semiconductor nanostructures have generated tremendous scientific interests as well as practical applications stemming from the engineering of low dimensional physics phenomena. Unlike 0D and 1D nanostructures, such as quantum dots and nanowires, respectively, 2D structures, such as nanomembranes, are unrivalled in their scalability for high yield manufacture and are less challenging in handling with the current transfer techniques. Furthermore, due to their planar geometry, nanomembranes are compatible with the current complementary metal oxide semiconductor (CMOS) technology. Due to these superior characteristics, there are currently different techniques in exfoliating nanomembranes with different crystallinities, thicknesses and compositions. In this work we demonstrate a new facile technique of exfoliating gallium nitride (GaN) nanomembranes with novel features, namely with the non-radiative cores of their threading-dislocations (TDs) being etched away. The exfoliation process is based on engineering the gallium vacancy (V_Ga) density during the GaN epitaxial growth with subsequent preferential etching. Based on scanning and transmission electron microscopies, as well as micro-photoluminescence measurements, a model is proposed to uncover the physical processes underlying the formation of the nanomembranes. Raman measurements are also performed to reveal the internal strain within the nanomembranes. After transferring these freely suspended 25 nm thin GaN nanomembranes to other substrates, we demonstrate the temperature dependence of their bandgap by photoluminescence technique, in order to shed light on the internal carrier dynamics.

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Rami T. ElAfandy, Mohammed A. Majid, Tien Khee Ng, Lan Zhao, Dongkyu Cha, and Boon S. Ooi "Chemical exfoliation and optical characterization of threading-dislocation-free gallium-nitride ultrathin nanomembranes", Proc. SPIE 9277, Nanophotonics and Micro/Nano Optics II, 927719 (13 November 2014); https://doi.org/10.1117/12.2071471

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KEYWORDS

Gallium nitride

Etching

Crystals

Raman spectroscopy

Semiconducting wafers

Transmission electron microscopy

Scanning electron microscopy

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