Fabrication of GaAs quantum rings by in-situ laser irradiation

In this work, after depositing a GaAs buffer layer (approx. 200nm) via molecular beam epitaxy, we subjected the GaAs substrate to in-situ irradiation by 15 laser pulses (pulse duration ∼10ns) with varying single-pulsed energies of 10mJ, 15mJ, 20mJ, and 30mJ, corresponding to samples A-D. For sample A, quantum rings with a density of 3.75×108/cm2 are observed, of which the average height and width are 1.4nm and 22.2nm, respectively. For sample B, the density, average height and width are 5×108/cm2, 2.5nm and 69.1nm. With an increase in laser energy, the density and size of sample C and D have increased to 7×108/cm2-3.6nm (height)-78.5nm (width) and 1×109/cm2-5.2nm (height)-86.1nm (width) respectively. Obviously, this novel technology that the GaAs quantum rings can be fabricated in-situ through multi-pulsed laser irradiation whilst the size and density of the quantum rings can be effectively adjusted by varying the laser energy would have significant applications in all types of semiconductor devices based on quantum rings in the future.