Pustaka Ilmiah Universitas Padjadjaran

Abstrak

Fabrikasi Dan Karakterisasi Pandu Gelombang Planar Polimer Terkonjugasi

Film tipis polimer terkonjugasi memegang peranan yang sangat penting dalam perkembangan berbagai piranti fotonik masa depan seperti untuk integrated optics, laser, LED, sel surya, transistor organik dan divais optik nonlinier. Pandu gelombang planar sangat cocok dikembangkan untuk integrated optics (IO), karena mudah difabrikasi dan merupakan optoboard bagi piranti fotonik di atas. Film tipis untuk pandu gelombang planar harus transparan, mempunyai indeks bias dan ketebalan yang homogen, mempunyai permukaan yang halus serta memiliki koefisien waveguide loss agw < 1 dB/cm. Mendapatkan film tipis yang berkualitas baik merupakan syarat utama untuk aplikasi, sehingga berbagai upaya dilakukan agar kinerja piranti fotonik optimal. Teknik spin-coating merupakan salah satu teknik yang sangat cocok untuk pembuatan pandu gelombang planar dengan kualitas optik yang baik. Optimalisasi parameter-parameter spin-coating untuk memperoleh film tipis berkualitas optik yang baik telah dilakukan pada tahun I yang menghasilkan emphirical rule dari spin-coating fim tipis polimer polistiren (PS), polyvinyl carbazole (PVK) dan poly[2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Hasilnya digunakan dalam fabrikasi pandu gelombang planar yang dilaksanakan pada tahun II. Penelitian ini bertujuan untuk memperoleh pandu gelombang planar dengan kerataan permukaan yang kecil, morfologi permukaan yang homogen dan koefisien waveguide loss agw < 1 dB/cm. Tahapan eksperimen adalah fabrikasi pandu gelombang planar, pengukuran koefisien agw dan pengukuran kerataan atau morfologi permukaan film tipis dari polimer PS, PVK dan MEH-PPV. Koefisien waveguide loss merupakan parameter krusial untuk menentukan apakah polimer dapat digunakan untuk aplikasi pandu gelombang planar atau tidak. Koefisien ini dipengaruhi oleh ketebalan, kerataan atau morfologi permukaan film dan panjang gelombang cahaya yang digunakan. Tujuan lainnya adalah untuk menghasilkan korelasi antara agw dengan kerataan dan morfologi permukaan film tipis.

Thin films of organic polymers play very important roles on the development of photonic integrated optics applications such as laser, light emitting diode (LED), photovoltaic cells and nonlinear optical devices. Optical waveguides are appropriate to be developed for integrated optics application due to easy of fabrication and they are relative easy to be integrated with other optical components. Optical planar waveguides can be made in the form of thin film of suitable materials that posses high refractive indices. Thin films have to posses good optical quality such as transparent in the work wavelength region, homogeniety in both refractive index and thickness. A lot efforts have been done in order to obtain good quality of thin films. They are several techniques for fabrication of thin organic films, e.g. vacuum evaporation, doctor-blading, spin-coating and dip-coating. Spin coating technique is widely used for fabrication of thin organic films or organic planar waveguides with good optical quality. In this research, we have used this technique to fabricate thin polymer film for planar waveguide application. The aim of our research is to obtain good quality of thin polymer films, e.q. transparent in the work wavelength region, homogeniety in both refractive index and thickness. There are three steps of experiment. First step, several parameters of spin coating such as type of solvent, substrate temperature, concentration of solution, spinning speed, spinning time and fabrication temperature were optimized to obtain good quality of thin films. From this step, a correlation between spin coating parameters and thickness and surface roughness of thin films (emphirical rule) was obtained. In the second step, we have fabricated thin films from other polymers, especially which are potential for integrated optical devices, by adjusting obtained parameters in the first step. A new emphirical rule was obtained. In the last step, we have measured optical properties of all thin films e.q. absorption coefficent and dispersion of their refractive indices. We have used experimental method in this research. We have used spin coating technique to fabricate thin polymer films. Alpa step profilomter was employed to measure thin films thickness (d) and their surface roughness (Ra). Meanwhile, UVvis spectrometer was used to measure the optical properties of thin polymer films. In the first year, we have fabricated thin films from three different polymers by use of spin coating technique. They are polystyrene (PS), polyvinyl carbazole (PVK) and a derivate of poly(para-phenylenevinylene), poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Spinning speed of spin coater and substrate temperature were variied. The results show that by optimization of thin film fabrication parameters, both the thickness and surface roughness of thin films can be controlled precisely. This emphirical rule could be used for other similar conjugated polymers.