The Study Of In-situ Pulsed Laser Etching InAs/GaAs(001) Quantum Dot

Semiconductor quantum dots,due to their atomic-like electronic and optical properties,tremendous applications ranging from electronic devices to photonic devices have been worldwide realized on them.One of the most prototypical case is the MBE self-assembled In As/GaAs QDs by S-K growth and their related-devices of photo-detector and laser etc.,have successfully been fabricated and well served in various social fields.However,to design and construct novel QD-devices for the cutting-edge applications of single photo emitter and quantum computation are asking for more controllability of QD fabrication particularly focusing on the site control.So far,the strategy of self-assembling QDs on prepatterned substrate is widely used for fabricating ordered QDs.However,some shortcomings still have greatly challenged the technology such as oxidation,pollution and etching damage etc.The experimental results show that the above mentioned problems can be effectively solved by laser direct writing interference nano patterned molecular beam epitaxy technology.In this paper,we studied the action characteristics of In As/GaAs quantum dots irradiated by in situ pulsed laser,and verified that pulsed laser can completely remove the quantum dots on the substrate surface.Through the experiments of laser intensity,surface temperature and number of pulses,the morphologies of quantum dots are studied,and a temperature dominated kinetic model of In-targeting laser-desorption and laser-diffusion is proposed.In high temperature,the shape of quantum dots remain unchanged,the overall size is reduced like a water droplet which is dried by thermal evaporation because of the laser-desorption effect.At low temperature,the shape of the quantum dots is collapsed from the 3D island to the 2D island because of the intensification of the laser-diffusion effect.The In As epitaxy on laser etched quantum dots as template indicates the selective desorption of laser on In As quantum dots.The quantum dot epitaxy on the surface of the template and the non-irradiating GaAs substrate has a similar evolution law,which shows that the in-situ laser etching technology is compatible with the molecular beam epitaxy.