MOVPE Growth of GaN via Graphene Layers on GaN/Sapphire Templates.

Kazimieras Badokas,Giedrius Juška,Martynas Skapas,Tadas Malinauskas,Arūnas Kadys,Jūras Mickevičius,Benjaminas Šebeka,Dominykas Augulis,Ilja Ignatjev

doi:10.3390/nano12050785

Kazimieras Badokas, Giedrius Juška + Show 7 more

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https://doi.org/10.3390/nano12050785

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Abstract

The remote epitaxy of GaN epilayers on GaN/sapphire templates was studied by using different graphene interlayer types. Monolayer, bilayer, double-stack of monolayer, and triple-stack of monolayer graphenes were transferred onto GaN/sapphire templates using a wet transfer technique. The quality of the graphene interlayers was examined by Raman spectroscopy. The impact of the interlayer type on GaN nucleation was analyzed by scanning electron microscopy. The graphene interface and structural quality of GaN epilayers were studied by transmission electron microscopy and X-ray diffraction, respectively. The influence of the graphene interlayer type is discussed in terms of the differences between remote epitaxy and van der Waals epitaxy. The successful exfoliation of GaN membrane is demonstrated.

Highlights

GaN/Sapphire Templates.In recent years, a novel approach to the growth of III-nitrides has emerged, based on 2D materials, such as graphene, as interlayers between the substrate and the epitaxial layer [1–3]
The initial GaN/sapphire template was prepared by the standard metalorganic vapor phase epitaxy (MOVPE) growth of the GaN layer on a 2-inch c-plane sapphire substrate
The thickness of the GaN/sapphire template was 2.7 μm; its surface was smooth with the root mean square (RMS) surface roughness value of 0.2 nm, evaluated using AFM

Summary

Introduction

A novel approach to the growth of III-nitrides has emerged, based on 2D materials, such as graphene, as interlayers between the substrate and the epitaxial layer [1–3]. Compared to the usual buffer layers, the graphene interlayer has some advantages owing to the weak van der Waals (vdW) bond at the epilayer/graphene interface; the thermal expansion and lattice mismatch requirements are relaxed [4], resulting in reduced defect density [5–7], and the epilayer can be mechanically exfoliated and transferred to any substrate of interest [3,8,9]. The remote epitaxy and graphene-mediated exfoliation have been demonstrated for several material systems, including III-N [8,9,11,12], III-V [10], II-VI [9], transition metal dichalcogenides [13], perovskites [14], and other complex oxides [15]. The critical step in this approach is the graphene layer transfer. Depending on the transfer method, cracks, wrinkles, residue, and contamination might decrease the quality of the graphene layer [19–21], and significantly affect the epilayer growth

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