Feature size effects in chemically assisted ion beam etching of InP-based photonic crystals

This work addresses feature size effects (the lag-effect and roughness development) in chemically assisted ion beam etching (CAIBE) etching of InP-based photonic crystals. Photonic crystal fields with varying hole size and periods were etched with different etching times. The slope of the etch depth versus diameter curves (lag-curves) reveals a hole size dependence, with a critical aspect ratio higher than 25. A model for the etch rate specific to Ar/Cl<sub>2</sub> CAIBE is proposed. We calculate the etch rate using a physico-chemical model which takes in to account the effect of Ar-ion sputtering and surface chemical reactions. In addition, it combines the aspect ratio dependence of the gas conductance of the etched holes. The origin and evolution of the bottom roughness of the etched holes is examined. The impact of the feature size dependence of the etching on the photonic crystal optical properties is then assessed by measuring the quality-factor of one-dimensional Fabry-Perot cavities using the Internal Light Source method, and discussed in terms of hole shape and depth. A systematic trend between the determined quality factor (Q) and the lag-effect is evidenced: Q decreases from about 250 to 60 when the hole depth drops from 5 &mu;m to 2 &mu;m.

International Society for Optical Engineering, Bellingham WA, WA 98227-0010, United States
Dept. of Microelectronics and Information Technology, Royal Institute of Technology, S-16440 Kista, Sweden
Compilation and indexing terms, Copyright 2006 Elsevier Inc. All rights reserved
Chemically assisted ion beam etching (CAIBE)
Lag effect
Photonic crystal
Gas conductance
Clausing factors
1D cavities

 Record created 2007-04-03, last modified 2018-03-18

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