The latest breakthrough comes from a research conducted by US scientists, who claim to have established a new and improved way to grow indium gallium nitride (InGaN) crystals, that can be used not only to create the most efficient solar cells to date, but also to improve the existing LED technology.
The research was funded by the Office of Naval Research, the Air Force Office of Scientific Research, and the Defense Advanced Research Projects Agency as well as the National Science Foundation, and it dealt with the main limitation that scientists have been trying to overcome when it comes to using InGaN– lack of uniformity in the composition of the material.
But before we get into details, here is a brief background on InGaN and its potential. The material became famous when Solar Junction developed a super efficient solar cell, which has a layer of antimony-doped InGaN. This cell had record-breaking characteristics because of the band gap characteristics of Gallium. But the material has always been very difficult to grow into a sheet, due to its inconsistent composition, which does not allow smooth fitting of the layers.
The scientists from Arizona State University and the Georgia Institute of Technology, decided to tackle this, by trying to remove irregularities in the atomic structure of the new crystal. The method that they developed is called modulated epitaxy, which is similar to the well established epitaxial deposition method, known since the 1960s, and it is essentially an application of an extra thin layer of InGaN material to a substrate.
This resulted in a production of a much larger quantity of film, which does exactly what scientists have been trying to achieve for decades. The new crystal is both uniform in structure and has the needed trait of luminosity. The key, according to the team, was hidden in the strain relaxation that occurs at the first atomic layer of crystal growth.
Thanks to this method, the team was able to produce the material that promises increase of efficiency of solar cells by as much as 10%.