Monolithic Free-Standing Large-Area Vertical III-N Light-Emitting Diode Arrays by One-Step h-BN-Based Thermomechanical Self-Lift-Off and Transfer

Abstract

We demonstrate the fabrication of vertical InGaN light emitting diodes on large-area freestanding membranes, using a mechanical lift-off technique enabled by 2D h-BN. 30-μm-thick electroplated copper deposited on the epilayer (i) gives rigidity to the structure, preventing crack generation, (ii) functions as a back mirror and as a heat sink, and (iii) enables one-step self-lift-off and transfer of LED structures from h-BN/sapphire during a thermal treatment at 100°C. Free-standing arrays of LEDs on thick membranes were processed and their electro-optical performance characterized. This approach can provide a solution for the fabrication of low cost, wafer scale, crack-free, and highly reproducible free-standing arrays of vertical LEDs with up to centimeter-size areas.

Recent Advances in Mechanically Transferable III‐Nitride Based on 2D Buffer Strategy

“…For this purpose, Karrakchou et al. in 2021 [ 97 ] fabricated vertical InGaN‐based LEDs on large‐area free‐standing membranes using the 2D h‐BN‐assisted mechanical lift‐off technique. On top of the LED structure, they deposited a thick electroplated copper layer.…”

“…A critical step in the VTF-LED manufacturing process is the separation of the epilayer from the native substrate. For this purpose, Karrakchou et al in 2021 [97] fabricated vertical InGaN-based LEDs on large-area free-standing membranes using the 2D h-BN-assisted mechanical lift-off technique. On top of the LED structure, they deposited a thick electroplated copper layer.…”

Freestanding Membranes for Unique Functionality in Electronics

“…The layer transfer methods enable epitaxial layers to be separated from the host substrate after epitaxy and transferred to a foreign substrate, leading to extreme freedom in making heterostructures. , These advantages can provide new functionality to electronic devices, including new heterointegration and new device structures through layer transfer, new physical phenomena from these new structures, and unprecedented improvement of the device performances. Because of such benefits, various lift-off techniques have been actively developed, such as chemical lift-off, mechanical spalling, laser lift-off, and two-dimensional (2D) material-assisted layer transfer (2DLT). − In addition, the importance of the recent emerging heterointegration is increasing interest in layer transfer technology. In this review, we comprehensively summarize recent developments on inorganic freestanding membranes (or epilayers) that have been realized through layer transfer techniques and their applications along with their challenges and perspectives.…”

Design and fabrication process flow for high-efficiency and flexible InGaN solar cells

“…Finally, for the fabrication of flexible solar cells, we propose to use the very recently developed self-lift-off and transfer (SLOT) process. This technology has been used for the development of flexible LEDs [31]. The method involves the deposition of a 30m thick copper layer on the solar cell structure grown on 2D h-BN/sapphire substrate.…”