In-situ Indium-assisted Laser Etching Of GaAs Surface

Semiconductor processing technology has a wide range of applications in the fields of integrated circuits,wireless communications,and photodetectors.With the miniaturization of new devices,it is imperative to explore to develop efficient nanofabrication approaches with ultra-high processing accuracy,even atomic resolution to avoid the adverse effects of tiny defects on the device.Conventional semiconductor atomic-level etching technologies still have problems such as oxidation,parasitic pollution,serious damage,high cost,and low efficiency,so it is difficult to meet the practical manufacture requirements.Therefore,it has become more and more significant to find new semiconductor atomic-level etching techniques.In this thesis,combining molecular beam epitaxy(MBE)and pulsed laser irradiation,a new method was developed to modify semiconductor surface at an atomic level,which is non-destructive,no contamination,without oxidation and highly controllable.First in the world,the strategy of "utilizing in-situ indium-assisted laser to achieve atomic-level etching of ?-? semiconductor materials" was proposed conceptually and experimentally demonstrated on GaAs substrates.The results show:1.With different laser intensities,the in-situ In-atom-assisted atomic-scale laser etching would produce two morphologies(cracked atomic terraces,nanoholes).When the pre-deposition thickness of InAs on GaAs surface exceeds?0.5ML,laser could effectively etch up the structures of nano holes on GaAs surface,and then both the size and density of these nano-holes could further amplify with the increase of the pre-deposition amount under the same laser energy.When the thickness exceeds?1.0ML,such amplification tendency will obviously slow down.2.In order to control the size of nanohole further,a method called step-by-step etching was used to further enlarge the size of the nanoholes.3.By introducing four-beam laser interference patterns on a thick InGaAs alloy layer grown by MBE on GaAs,a non-destructive periodic large-size(nanoscale)"holes" can be fabricated,which was completely different from the nanoholes on the GaAs surface modified by InAs wetting layer.It confirmed that the higher the degree of mixing of the In,Ga,and As atoms,the higher the efficiency of atomic layer etching.Compared to traditional methods,the whole fabrication process based on this new method in a high vacuum environment,without introducing any impurities,the etching depth of the material surface was limited to 3-5 atomic-layer thickness,and the etching could be controlled by atomic scale with controllable laser irradiation.This research is of great significance for the realization of device miniaturization based on semiconductor atomic level etching technology.