Epitaxial lateral mask overgrowth which occurs during GaN selective epitaxy has been studied using linear mask features. The lateral growth varies between its maximum and minimum over a 30° angular span and exhibits hexagonal symmetry. Vertical growth follows an opposite trend, with lateral growth maxima, and vertical growth minima occurring for lines parallel to the GaN ⟨10•0⟩. Large variations in the lateral growth are also obtained through variations in the growth temperature andNH3flow. Under proper growth conditions, lateral to vertical growth rate ratios of up to 4.1 can be achieved, resulting in significant lateral mask overgrowth and coalescence of features without excessive growth times. ©1997 American Institute of Physics.