Wet etching of sol-gel deposited lead lanthanum zirconate titanate for photonic crystal applications

Abstract

Arrays of lead lanthanum zirconate titanate disks are fabricated on Pt electrodes by wet etching of thin films processed from sol-gel precursors, which may be applicable as defect cavities with electrically tunable resonance wavelength when embedded inside 2-D Si photonic crystals. Using e-beam lithography followed by sputtering and liftoff, Pt etch masks with diameters down to 1µm are deposited on pyrolyzed PLZT films. Wet etching using diluted hydrochloric acid generates discrete PLZT disks with integrated top and bottom Pt electrodes. The dimensions of the PLZT disks are determined by the diameter of the Pt etch mask, although undercutting becomes a significant issue as etch mask size decreased. The effects of varying PLZT pyrolysis temperature on the etching rate and film quality after sintering are examined. Dielectric testing of wet etched PLZT film after sintering showed that the devices have short circuited, suggesting that the deformation of the top Pt electrode over the undercut PLZT during sintering may significantly hinder the applicability of the current wet etching technique. Alternate methods for the patterning of PLZT for integration into photonic crystals are proposed.

Coupling of piezoelectric effect with electrochemical processes

“…One such heterojunction that is particularly dynamic is that which exists between a piezoelectric material and a chemical solution [6,7]. Piezoelectric fields have been used to control the corrosion rate of materials exposed to etchant solutions [8][9][10][11][12][13][14][15][16][17][18], selectively control the energetics and spatial separation of adsorbed [19,20] and photo-deposition materials [21][22][23][24][25][26][27][28], and have even been used to directly drive electrochemical reactions across piezoelectric/solution interface [6,7,[29][30][31].…”