CI2/O2-inductively coupled plasma etching of deep hole-type photonic crystals in InP

We have developed an inductively coupled plasma etching process for fabrication of high-aspect-ratio hole-type photonic crystals in InP, which are of interest for optical devices involving the telecommunication wavelength of 1550 nm. The etching was performed at 250 °C using Cl2/O2 chemistry for sidewall passivation. The process yields nearly cylindrical features with an aspect ratio larger than 10 for hole diameters near 0.25 µm. This makes them very suitable for high-quality photonic crystal patterns

Cl2/O2-inductively coupled plasma etching of deep hole-type photonic crystals in InP

Kavli Institute of Nanoscience DelftApplied Science

CI2/O2- and CI2/N2-based inductively coupled plasma etching of photonic crystals in InP: sidewall passivation

We have fabricated two-dimensional photonic crystals in InP-based materials with Clz-based inductively coupled plasma etching. To obtain vertical sidewalls, we employ sidewall passivation through addition of Nz or U2 to the plasma. With the Clz/Oz-process we are able to etch 3.2 pm deep holes that have nearly cylindrical shape in the upper 2 pm. The first optical results illustrate the feasibility of our approach, showing over 30 dB transmission reduction in the rK-stopband

Inductively coupled plasma etching of deep photonic crystal holes in InP using Cl2

We have investigated ICP-etching of deep photonic crystal holes in InP using solely Cl2 as supplied etching gas. The influence of process parameters on hole geometry is discussed and optical test results are reporte

Wavelength tuning of planar photonic crystals by local processing of individual holes

Tuning of the resonant wavelength of a single hole defect cavity in planar photonic crystals was demonstrated using transmission spectroscopy. Local post-production processing of single holes in a planar photonic crystal is carried out after selectively opening a masking layer by focused ion beam milling. The resonance was blue-shifted by enlargement of selected holes using local wet chemical etching and red-shifted by infiltration with liquid crystals. This method can be applied to precisely control the resonant frequency, and can also be used for mode selective tuning

Local digital etching and infiltration for tuning of a H1- Cavity in deeply etched InP/InGaAsP/InP photonic crystals

Local post-production processing of single holes in a planar photonic crystal is demonstrated by selectively opening a masking layer by focused ion beam milling. Local tuning was optically demonstrated by both blueshifting and subsequent red-shifting the resonance frequency of a point defect cavity. Since only a few holes of the PC are affected by the post-processing, the Q-factor is not significantly changed. This method can be applied to precisely control the resonant frequency, and can also be used for mode selective tuning

Deep hole InP photonic crystals infiltrated with solid polymers and liquid crystals

A procedure to etch deep photonic crystal holes in InGaAsP and subsequently fill them with a low index material such as liq. crystal or a solid polymer has been developed. Successful infiltration was proven by optical transmission measurement and in the case of solid polymer also by cross section inspection

Fabrication, measurement and tuning of a photonic crystal H1-cavity in deeply etched InP/InGaAsP/InP

A point defect cavity (H1) was fabricated by deep etching in the InP/InGaAsP/InP system. The optical properties of the devices were experimentally investigated by transmission spectroscopy yielding a Q-factor of ~65. The resonance frequency of the defect cavity was shifted, by infiltrating the surrounding holes with both a polymer and liquid crystal. Furthermore, the transmission was enhanced by a factor « 5 as a result of the filling

Influence of ICP etching on surface morphology of InP substrates

We have investigated the effect of Inductively Coupled Plasma (ICP) etching using a C12-CHrH2 chemistry on the surface morphology of InP substrates. We have observed a strong dependence of the surface morphology on the etching times of semi-insulating ( s i ) InP-wafers. Pillars are formed after a sufficient etching time. Photoluminescence characterization revealed a strong correlation between morphology and PL signal intensity

Deep dry etching process development for photonic crystals in InP-based planar waveguides

Chlorine-based inductively coupled plasma etching processes are investigated for the purpose of etching two-dimensional photonic crystals in InP-based materials. Etch rates up to 3.7 mm/min and selectivity"s to the SiN mask up to 19 are reported. For the removal of indiumchloride etch products both the application of elevated temperatures and high ion energy"s are investigated. The reactor pressure is an important parameter, as it determines the supply of reactive chlorine. It is shown, that N2 passivates feature sidewalls during etching, improving the anisotropy. Ions that impact onto the sidewalls, either directly or after scattering with the SiN-mask or hole interior, cause sidewall etching. Highly directional ion bombardment and vertical sidewalls in the SiN-mask are therefore crucial for successful etching of fine high aspect ratio structures