Inorganic Semiconductors Guide New Optoelectronic Devices

Inorganic compound semiconductors could potentially replace those developed with organic materials.

A research team from Seoul National University (SNU) has grown gallium nitride (GaN) microrods on graphene substrates, which may ultimately lead to the creation of transferrable LEDs, enabling the fabrication of bendable and stretchable optoelectronics devices.

The very stable and inactive surface of graphene offers a small number of nucleation sites for GaN growth, according to the researchers.

The growth of GaN micro-rods on graphene substrates could lead to bendable, stretchable optoelectronics devices. Courtesy of Seoul National University.

GaN microstructures and nanostructures show potential as LEDs, given their variable-color light emission and high-density integration properties.

According to the researchers, this type of inorganic compound semiconductor possesses superior optical, electrical and mechanical properties than conventional ones made from organic materials.

The research team created GaN microstructure LEDs on graphene substrates using a catalyst-free metal/organic chemical vapor deposition (MOCVD) process that they had previously developed. Ultrathin graphene film was used as a substrate because it provided the desired flexibility and mechanical strength; it is also chemically and physically stable at temperatures in excess of 1000° C.

When the research team tested the bendability and reliability of GaN micro-rod LEDs fabricated on graphene, it found that the resulting flexible LEDs showed intense electroluminescence (EL) and were reliable.

“There was no significant degradation in optical performance after 1000 bending cycles,” said Kunook Chung, a graduate student in SNU’s physics department.

The study’s findings could enable the use of large-scale and low-cost manufacturing processes to develop next-generation electronics and optoelectronics devices, such as flexible and wearable LED displays for commercial use.

The research was published in APL Materials (doi: 10.1063/1.4894780).

For more information, visit: www.useoul.edu.