In situ lift-off of InAs quantum dots by pulsed laser irradiation

InAs/GaAs quantum dots (QDs) grown by molecular beam epitaxy were subjected to in situ irradiation using a mono-beam pulsed laser. The evolution of the QD morphology was investigated as a function of irradiation intensity at temperatures of 525 °C and 480 °C. The temperature was found to exert a considerable influence on the reaction of the QDs to the irradiation. At the higher temperature (525 °C), both the height and width of the InAs QDs gradually decreased with increasing irradiation intensity, which was ascribed to the dominant effect of the laser desorption of indium. In contrast, at the lower temperature (480 °C), the height of the InAs islands decreased with increasing irradiation intensity while the width exhibited unexpected broadening, which was attributed to a combination of laser desorption and laser diffusion of indium. Remarkably, at the higher temperature, laser irradiation above a certain threshold intensity resulted in the lift off of the InAs QDs to afford a clear, smooth, and perfect GaAs surface. Through subsequent growth of QDs on this surface, it was found that the QDs exhibited the same nucleation properties and optical quality as the common Stranski–Krastanov mode on an as-prepared GaAs surface. Therefore, we have developed a technology for the damage-resistant fabrication of QDs using in situ pulsed laser irradiation (LIR), which is expected to find potential applications in the manufacture of patterned QDs upon upgrading the mono-beam irradiation to multi-beam interference irradiation in the future.