To determine the evolution of wear with GaN, the group subjected GaN to stresses by running slide tests in which the slide distance and the corresponding number of cycles were varied. According to the group, when performing wear measurements of unknown materials, they typically slide for 1000 cycles. In this case, they had to increase to 30,000 reciprocating cycles for the wear scars to be measurable. According to the researchers, this range in wear resistance is caused by factors, including environment, crystallographic direction and humidity.
"The wear resistance of GaN," said Nelson Tansu, director of the Center for Photonics and Nanoelectronics, "gives us the opportunity to replace the multiple layers in a typical semiconductor device with one layer made of a material that has excellent optical and electrical properties and is wear-resistant as well.
"Using GaN, you can build a device in a platform without multiple layers of technologies. You can integrate electronics, light sensors and light emitters and still have a mechanically robust device. This will open up a paradigm for designing devices. And because GaN can be made thin and strong, it will accelerate the move to flexible electronics."
In addition to its good wear performance, GaN also has good radiation hardness, which is an important property for the solar cells that power space vehicles. In outer space, these solar cells encounter large quantities of cosmic dust, along with x-rays and gamma rays, and therefore require a wear-resistant coating, which needs to be compatible with the cell's electronic circuitry. GaN provides the necessary hardness without introducing compatibility issues with the circuitry.