Fabricating,Peeling And Integrating Of GaAs Microtips

Scanning near-field optical microscopy(SNOM) is a novel and useful tool for the research and application down to nanometer scale.It utilizes the evanescent field confined at the tiny aperture for providing images of object surfaces with a resolution beyond the classical optical diffraction limit,and will have great influences not only in the fields of physics,chemistry, biology and material science,but also in medicine and information technology.One of the most important potential applications may be found in ultrahigh density optical data storage. For this application,a promising architecture of monolithic integrated SNOM sensor composed of a pyramidal microtip,a vertical-cavity surface-emitting laser(VCSEL) cavity and a pin monitor has been proposed.Take current technology into account,fabricating the GaAs micrtip with better quality and integrating the tip onto the VCSEL wafer with a pin monitor becomes the key to realize the integrated SNOM sensor.In this paper,the technology of GaAs microtips fabrication by selective liquid phase epitaxy is introduced.And the tips are improved by changing the method of fabricating SiO₂ layer;Two selective etching methods for microtips peeling off has been presented:HCl solution selective wet etching Al_0.7Ga_0.3As layer and NH₃H₂O-H₂O₂ solution selective wet etching GaAs substrate.Positive photoresist is introduced to protect tips from attack during the process.Scanning electron microscopy images show that GaAs tips can be successfully peeled off without any damage by this technique.Then a new agglutinating integration of tips has been presented.Positive photoresist and UV glue have been utilized to integrate tips and the loss of both of them has been measured.The result shows that the UV glue is a suitable material for tips integration because of its tiny light loss.This method can integrate tips successfully and the tips have been integrate onto VCSEL,AFM cantilever and fiber. Scanning electron microscopy images show that GaAs tips have not been damaged during the integration process.