Fabrication of Photonic Crystals devices Hamidreza khashei

Outline Introduction What is photonic crystal ? Types of photonic crystal Applications of photonic crystal The main steps of the procedure used to fabricate the components New fabrication techniques for high quality photonic crystals Conclusion Future Work References

Introduction What is photonic crystal ? Types of photonic crystal 1887 Photonic crystals are those that manipulate how photons are absorbed or reflected off of them. Photonic crystals are made of nanoscale structures that either allow or block individual wavelengths of light, depending on the frequency variations of their dielectric coefficients. Types of photonic crystal 1887 1987

Introduction Applications of photonic crystal Photonic crystals are attractive optical materials for controlling and manipulating the flow of light. One dimensional photonic crystals are already in widespread use in the form of thin-film optics with applications ranging from low and high reflection coatings on lenses and mirrors to color changing paints and inks. Higher dimensional photonic crystals are of great interest for both fundamental and applied research, and the two dimensional ones are beginning to find commercial applications. The first commercial products involving two-dimensionally periodic photonic crystals are already available in the form of photonic crystal fibers, which use a microscale structure to confine light with radically different characteristics compared to conventional optical fibers for applications in nonlinear devices and guiding exotic wavelengths. The three-dimensional counterparts are still far from commercialization but offer additional features possibly leading to new device concepts (e.g. optical computers), when some technological aspects such as manufacturability and principal difficulties such as disorder are under control.

The main steps of the procedure used to fabricate the components Design preparation: The components required are drawn with mask editor software and converted into the EBL file format. Cleaning the substrate: The substrate is cleaned on a spin-coater (Karl Suss RC8) with acetone, ethanol, and isopropanol, and it is finally blown-dry with N2. Spin-coating of the resist: A ∼100 nm thick layer of resist (ZEP-520a) is spun on top of the substrate. Pre-baking: The sample is then baked for 2min on a hotplate at 130◦C, in order to remove the solvent and harden the resist. Cleaving the substrate: The substrate is cleaved in pieces of about 1.2× 5 cm2 in order to fit in a 2" carrier of the EBL machine and blown-dry with N2 in order to remove any dust on the substrate.

The main steps of the procedure used to fabricate the components EBL writing: The pattern is written in the resist using EBL. Development of the pattern in the resist: The exposed regions are dissolved with the developer ZED-N50 for 1 minute, and the sample is rinsed 30 s with isopropanol.

The main steps of the procedure used to fabricate the components Post-baking: Before the etch, the sample is baked for 5 minutes on a hotplate at 110◦C. Dry etching: The pattern is transferred fromthe resist to the top silicon layer using a dry etch. Lift off of the resist: The residual resist is removed with an oxygen plasma. Cleaving the sample: The sample is finally cleaved in order to access the waveguides.

New fabrication techniques for high quality photonic crystals

Conclusion Future Work We have shown new fabrication techniques of making high quality 2D and 3D photonic crystals by using high resolution lithography and anisotropic ion etching. A 2D photonic crystal with 600 nm period and 300 nm linewidth was fabricated by etching through Si/SiO2 multilayers . Future Work Because of the low efficiency of the conventional method of RIE another system, Advanced Silicon Etch (ASE), was used to transfer fine detailed structures to the top silicon layer. This is an ICP system where the RF electric field is provided by a coil surrounding the plasma chamber. This configuration gives a higher plasma density, which results in a 5−10 times higher etching rate than in traditional RIE systems. In addition, the pressure can be kept low in the chamber, reducing the ion scattering in the plasma and thus maintaining the directionality of the ion bombardment .

References [1] : Theory and technology of semiconductor devices , aut press , hassan kaatuzian [2] : Photonic Vol-2 , aut press , hassan kaatuzian [3] : New fabrication techniques for high quality photonic crystals , Chuan C. Cheng and Axel Scherer (Received 30 May 1997; accepted 6 August 1997) [4] : Silicon-based components: 2D photonic crystal components and semiconductor nanocrystals , Amelie Tetu (PhD thesis November 2007) [5] : Introduction to Photonic Crystals , Steven G. Johnson and J. D. Joannopoulos, MIT , 3rd February 2003 [6] Fabrication of Two-Dimensional Photonic Crystal Single-Defect Cavities and their Characterization by Elastic Scattering , Ivan Alvarado-Rodriguez , 2003

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