Progress and prospects of III-nitride optoelectronic devices adopting lift-off processes
Wai Yuen Fu, H. W. Choi
Abstract
Lift-off processes have been developed as the enabling technology to free the epitaxial III-nitride thin film from a conventional growth substrate such as sapphire and silicon in order to realize a variety of novel device designs and structures not otherwise possible. An epitaxial lift-off (ELO) process can be adopted to transfer the entire film to an arbitrary foreign substrate to achieve various functions, including enhancement of device performance, improvement of thermal management, and to enable flexibility among others. On the other hand, partial ELO techniques, whereby only a portion of the thin-film is detached from the substrate, can be employed to realize unconventional device structures or geometries, such as apertured, pivoted, and flexible devices, which may be exploited for various photonic structures or optical cavities. This paper reviews the development of different lift-off strategies and processes for III-nitride materials and devices, followed by a perspective on the future directions of this technology.