Remote epitaxy and 2DLT for emerging technology

High-quality GaN film epitaxy traditionally necessitates the use of expensive single-crystalline wafers like SiC, Bulk GaN, or GaN templates. To mitigate the processing costs, the industry has widely adopted heteroepitaxy of GaN on silicon. However, this method is not without its challenges – a substantial 17% lattice mismatch between GaN and Si incurs high dislocations and defects.

Addressing this issue, we have employed remote epitaxy. This innovative process enables the growth of single-crystalline thin films on a substrate coated with 2D materials. One of the distinct advantages is the ease of exfoliating these films, paving the way for substrate recycling. In this approach, the atomically thin 2D buffer layer serves to partially screen the electrostatic potential of the underlying parent substrate (e.g., GaN, SiC) and facilitates ‘remote’ nucleation.

A noteworthy feature is the weak chemical bond between the 2D buffer layer and the epilayer. This allows remote epitaxial films to be easily detached at the 2D buffer interface, a process facilitated by straightforward mechanical exfoliation. Our efforts are particularly geared towards the cost-effective production of high-quality GaN membranes that can be seamlessly integrated with heat sinks.

Also, we are developing GaN wafer bonding technology. Successful GaN wafer bonding facilitates the integration of the exfoliated GaN membrane with Si CMOS technology and ensures secure attachment to heat sinks. Capitalizing on these technologies, we aim to meet the rising demands for innovative applications such as micro LEDs, flexible GaN RF devices, and circuits.