FAA2 : EPITAXIAL STRUCTURE FOR 3D PHOTONIC CRYSTALS AND PHOTONIC WIRE BRAGG GRATING DEVICES

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FAA2 EPITAXIAL STRUCTURE FOR 3D PHOTONIC
CRYSTALS AND PHOTONIC WIRE BRAGG GRATING DEVICES
Harold M. H. Chong, Marco Gnan, Marc Sorel and
Richard M. De La Rue Department of Electronics
and Electrical Engineering, Glasgow G12
8LT E-mail h.chong_at_elec.gla.ac.uk
Partners GLASGOW UNIVERSITY, CNRS-IOTA, CNRS-LPN
OUTLINE OF PROJECT
FABRICATION
This project is to demonstrate the fabrication
techniques of three-dimensional photonic crystal
(PhC) in epitaxial GaAs/AlGaAs epitaxial material
system. Two-dimensional PhC (air-hole array)
structures are first used as template to
transform the structure into wholly
three-dimensional system via dry-etch, thermal
oxidation and selective oxide wet etch process.
The GaAs/AlGaAs epitaxial material consists of 5
pair of mirror stack with total thickness of 1.8
?m.
The initial two-dimensional PhC pattern
structures are generated by direct write
electron-beam lithography. Large beam spot
lithography technique is used to generate a large
PhC pattern area 1. The pattern transfer from
the e-beam resist, silica etch mask to the
GaAs/AlGaAs epitaxial layer is performed by
reactive-ion-etching (RIE) based on fluorine and
chlorine chemistry.
FABRICATION ISSUES
The first generation of the 2D-3D PhC structure
is fabricated on GaAs/AlAs epitaxial material.
After dry etching of the III-V materials
through the mirror stack thickness, the PhC
structures suffer delamination from the AlAs
material once exposed to the atmosphere. The SEMs
below show the delaminated PhC structures before
thermal oxidation process. Epitaxial layer with
Al0.93Ga0.07As or Al0.95Ga0.05As material is
expected to lessen the delamination damages.

• Scanning electron micrographs of PhW 1st order
  Bragg grating with bi-lateral recess and total
  recess, designed for operation at ?o 1550 nm.
  SOI silicon core is 260 nm thick.