Investigation of pattern-orientation on stress in GaN grown on Si(111) substrate in lateral confinement epitaxy

GaN-on-Si has attracted wide interests for decades due to its advantages in cost effective opto-electronics and power electronics. The essential issue for GaN-on-Si epitaxy is the stress problem. Although many effeorts have beeen deovted, the remaining stress is still large and need to be further reduced. Lateral confinement epitaxy useing sub-millimeter scale patterened Si substrate is one effective approach to solve the stress problem. This work reports the first investigation of how the pattern-orientation influences the stress in GaN grown on Si(111) substrate. Through both experiment and simulation, we find that pattern-orientation play a role in the stress-relief of GaN epitaxy on Si. . For the pattern of square, a lower stress can be obtained when the intersect angle between the square edge and [11¯0]Si approaches 26° and 64°.