Remote heteroepitaxy of GaN microrod heterostructures for deformable light-emitting diodes and wafer recycle

Abstract

There have been rapidly increasing demands for flexible lighting apparatus, and micrometer-scale light-emitting diodes (LEDs) are regarded as one of the promising lighting sources for deformable device applications. Herein, we demonstrate a method of creating a deformable LED, based on remote heteroepitaxy of GaN microrod (MR) p-n junction arrays on c-Al2O3 wafer across graphene. The use of graphene allows the transfer of MR LED arrays onto a copper plate, and spatially separate MR arrays offer ideal device geometry suitable for deformable LED in various shapes without serious device performance degradation. Moreover, remote heteroepitaxy also allows the wafer to be reused, allowing reproducible production of MR LEDs using a single substrate without noticeable device degradation. The remote heteroepitaxial relation is determined by high-resolution scanning transmission electron microscopy, and the density functional theory simulations clarify how the remote heteroepitaxy is made possible through graphene.

Thru-Hole Epitaxy: Is Remote Epitaxy Really Remote?

“…Nevertheless, great attention has been paid to remote epitaxy since it has been believed to provide the great benefit of easy separation of the film, which is crystallographically aligned with a substrate. [1][2][3] Several other studies have also demonstrated the facile detachment of a film taken as evidence of remote epitaxy. [4][5][6][7][8] Strictly speaking, however, the easy detachability may not necessarily originate from the 'remoteness' of the remote epitaxy, but simply indicates that the binding between the film and space layer/substrate is weaker than the adhesion of the film to a detacher such as a thermal release tape.…”

“…2 Once the thickness of an inserted 2D material becomes above a critical value, the grown film is no longer crystallographically aligned with the underlying substrate. 2,3 The remote epitaxy strictly requires not only the defect-free growth of 2D material but also the state-of-the-art transfer with precise layer-number control. Nevertheless, great attention has been paid to remote epitaxy since it has been believed to provide the great benefit of easy separation of the film, which is crystallographically aligned with a substrate.…”

“…Extremely surprising studies reported that a crystalline film was epitaxially grown remotely without direct bonding to an underlying substrate despite an ultrathin defect-free 2D overlayer placed in-between, which was named as remote epitaxy. [1][2][3] An earlier study, for instance, claimed that GaN can be remotely grown through only up to two layers of graphene but not even a single layer of h-BN on underlying GaN. 2 This result was explained by the teleported influence of the GaN substrate that was not completely screened.…”

Group-III-nitride and halide-perovskite semiconductor gain media for amplified spontaneous emission and lasing applications

“…More recently, remote epitaxy using two-dimensional layers such as graphene has received substantial attention. For example, Jeong et al [57] reported the fabrication of deformable microrod LEDs and achieved substrate reuse. Zhao et al [4] and Min et al [58] further reported advances in nanowire and nanorod growth on unconventional substrates such as metal and quartz substrates.…”

The stability of graphene and boron nitride for III-nitride epitaxy and post-growth exfoliation

“…, Al 2 O 3 ) and that the substrate can be reused for the remote heteroepitaxy of a GaN microrod light emitting diode (LED). 18 Meanwhile, regarding the RE structure of III-nitride/graphene/III-nitride, the stability of the 2-D material on the decomposed III-nitride substrate warrants investigation because the growth temperature of III-nitride is higher than its decomposition temperature, 28 as shown in Fig. S1a, † which means that there is a possibility that column III atoms and N atoms generated from the decomposition of the III-nitride substrate affect graphene.…”