High-pressure crystallization of GaN for electronic applications

The results obtained with the use of pressure-grown GaN single-crystalline substrates allow us to draw the following conclusions important for the construction of In-free UV light emitting diodes and lasers and InGaN-based high-power blue lasers. (1) The application of pressure-grown GaN single-crystalline substrates allows us to grow near-dislocation-free layer structures by both metal– organic chemical vapour deposition and molecular beam epitaxy. (2) The elimination of dislocations leads to highly efficient UV emission from GaN and GaN/AlGaN quantum wells, which is impossible for strongly dislocated structures grown on sapphire. (3) At high excitations (e.g. in lasers), dislocations are also effective non-radiative recombination centres in InGaN-containing structures, so the elimination of these defects is crucial for better performance of blue lasers. In this paper, the optical and structural properties of the near-dislocation-free GaN-based structures leading to the above conclusions are discussed.