Remote epitaxy using graphene enables growth of stress-free GaN

Abstract

The properties of group III-Nitrides (III-N) such as a large direct bandgap, high melting point, and high breakdown voltage make them very attractive for optoelectronic applications. However, conventional epitaxy on SiC and sapphire substrates results in strained and defective films with consequently poor device performance. In this work, by studying the nucleation of GaN on graphene/SiC by MOVPE, we unambiguously demonstrate the possibility of remote van der Waals epitaxy. By choosing the appropriate growth conditions, GaN crystals can grow either in-plane misoriented or fully epitaxial to the substrate. The adhesion forces across the GaN and graphene interface are very weak and the micron-scale nuclei can be easily moved around. The combined use of x-ray diffraction and transmission electron microscopy demonstrate the growth of stress-free and dislocation-free crystals. The high quality of the crystals was further confirmed by photoluminescence measurements. First principles calculations additionally highlighted the importance of the polarity of the underlying substrate. This work lays the first brick towards the synthesis of high quality III-N thin films grown via van der Waals epitaxy.

Impact of 2D–3D Heterointerface on Remote Epitaxial Interaction through Graphene

“…Remote epitaxy and graphene-mediated exfoliation have been demonstrated for several material systems, including III−V, III−N, II−VI, perovskites, and other complex oxides, 6−13 versatility of the approach for diverse applications and heterogeneous integration. Although the underlying physics and principles of remote epitaxy have been theoretically investigated, 7,9,14,15 experimental environments could be vastly different from the general assumptions used in theoretical study, which is that both the substrate and the graphene layer are pristine without any defects, residue, or contamination. Furthermore, even if graphenecoated substrates are prepared to satisfy such conditions, the harsh epitaxy environment could also alter the graphene or the substrate properties and thus influence the formation of remote epitaxial films.…”

“…Although the underlying physics and principles of remote epitaxy have been theoretically investigated, ,,, experimental environments could be vastly different from the general assumptions used in theoretical study, which is that both the substrate and the graphene layer are pristine without any defects, residue, or contamination. Furthermore, even if graphene-coated substrates are prepared to satisfy such conditions, the harsh epitaxy environment could also alter the graphene or the substrate properties and thus influence the formation of remote epitaxial films.…”

Strain Engineering to Release Trapped Hole Carriers in p-Type Haeckelite GaN

“…In most fabrications of GaN devices, w -GaN is loaded on a sapphire substrate due to their similar hexagonal lattice structures on the interface despite the huge lattice mismatch of ∼17%. We expect that 4|8-GaN layers can be grown on rectangular substrates such as rock salt MgS and fluorite UO 2 that have only moderate lattice mismatches of −1.9 and +1.7% with respect to 4|8-GaN. , On the other hand, the epitaxial growth of GaN thin film has been examined on a graphene layer, which would stabilize 4|8-GaN instead of w -GaN for an atomically thin thickness of the GaN layer (2–18 GaN atomic layers) as predicted by theoretical studies. − Such films can be easily transferred to more fixable substrates for the strain control analogously to existing two-dimensional materials. , …”

Polarization‐Driven‐Orientation Selective Growth of Single‐Crystalline III‐Nitride Semiconductors on Arbitrary Substrates

“…In fact, several pioneering studies have demonstrated the possibility of growth of single-crystalline GaN on graphene, either by van der Waals epitaxy [18][19][20][21][22][23][24][25] or remote epitaxy. [26][27][28][29] However, most of the substrates underlying the graphene are still limited to be single crystalline. In addition, the physics behind the growth mechanism is still controversial.…”