Deep Elastic Strain Engineering of Free-Standing GaN Microbridge
Journal
Physical Review X
Journal Volume
16
Journal Issue
1
Start Page
011014
ISSN
2160-3308
Date Issued
2026-01-23
Author(s)
Fan, Sufeng
Wang, Heyi
Chou, Chang-Ti
Chen, Juzheng
Han, Ying
Zhou, Jingzhuo
Li, Xiaocui
Li, Ju
Lu, Yang
Abstract
Gallium nitride (GaN) as a direct band gap semiconductor played a central role in the historical development of efficient blue light-emitting diode and laser diode, in which its intrinsic wide band gap shrinks through the addition of indium (In), thus tuning the color of the light by changing the chemistry. This alloying approach, however, does not allow for dynamic and reversible modulation of the band gap and emission color. Here we show that ultralarge tensile elastic strain can be introduced in microfabricated single crystal GaN microbridges and offer an unprecedented opportunity to modulate its band structure and optoelectronic properties continuously through deep elastic strain engineering. The elastic strain-induced energy band gap modulation was characterized and quantified by in situ cathodoluminescence (CL) as well as via strained GaN devices inside a scanning electron microscope. The CL emission of deeply strained (>5%) GaN microbridges has shown substantial band gap reduction from ∼3.4 to 2.96 eV (∼365 to 420 nm in wavelength), making its optical emission shift from invisible or UV to the blue visible regime. Experimental results agree well with ab initio calculation of the change in band gap with increased strain. This dynamic, reversible, and well-controllable strain engineering would facilitate novel device applications in power electronics and optoelectronics.
Publisher
American Physical Society (APS)
Type
journal article