Georgia Institute of Technology UMI2958 | Georgia Institute of Technology | Atlanta, GA

This new technique uses a combination of van der Waals epitaxy of h-BN and selective area growth techniques that results in individual GaN-based devices such as LEDs, HEMT transistors, or solar cells that can be easily removed from the sapphire substrate and placed on other supports. Given that GaN and Sapphire are some of the hardest and strongest materials around, this is quite the trick!

The UMI researchers have grown self-organized GaN nanorod LED devices that were mechanically transfered to another substrate.  Hexagonal h-BN provided a key role in decoupling substrate from nanodevice and permitting lift-off.  This new technology is demonstrated at the wafer scale and can result in commericalization of nano-LEDs and other nanoscale nitride optoelectronic devices.

Breakthrough in MOCVD growth facilitates pick-and-place of optoelectronic nitride devices.  The discovery behind the growth technique is that boron nitride grows as a 2-D material on sapphire but in a highly disorganized form on silica. Subsequent gallium nitride based materials grow well on h-BN on sapphire, but not on amorphous BN on silica.  By prepatterning sapphire templates with silica then growing h-BN and then nitride based device structures, individual devices can be mechanically separated, eliminated needs for wafer dicing.  

2-D materials are promising for the creation of ultra-cheap flexible electronics using special purpose optoelectronic semiconductors such as Gallium Nitride.  A recent collaboration has led to major advances in the ability to transfer of 2-D materials for device fabrication and in the understanding of a technique called "remote epitaxy", which allows the growth of arbitrary materials on 2-D layers. These layers can then be easily transfered to other supports or transfered and integrated with other semiconductor materials.  This breakthrough technique has the potential to make devices based on 2-D materials commercially viable. 

A team of semiconductor researchers based in France has used a boron nitride separation layer to grow indium gallium nitride (InGaN) solar cells that were then lifted off their original sapphire substrate and placed onto a glass substrate.