Dissertation in the field of micro- and nanotechnology, Ali Shah

The title of thesis is ”Black silicon technology and applications”.

Black silicon is a textured Silicon surface, composed of densely packed and randomly distributed micro- and nanostructures. For a broad spectrum of incoming light, the micro- and nanostructures enhance absorption and scattering, whereas the reflection is remarkably suppressed. The surface appears black to the naked eye and therefore the material is referred to as black silicon. This thesis presents the development of black silicon and demonstrates its potential for different applications. The work performed in this thesis is divided into two parts. In the first part, fabrication aspects of black silicon are studied. Influence of the process parameters is analyzed and through careful optimization, different types of black silicon are achieved. In the second part of this thesis, both standard and novel techniques are employed to demonstrate various applications. Superhydrophobic, hydrophobic and superhydrophilic surfaces are achieved side by side on the same template. Droplet confinement to such patterns is used to demonstrate self-alignment of microchips which is particularly useful for advanced packaging applications. Finally, optical properties of black silicon are enhanced by fine tuning the black silicon surface structures and deposition of thin films. The resulting black silicon exhibited remarkable antireflection characteristics not only in UV-VIS but also in NIR spectrum. The techniques developed in this thesis provide valuable guidelines for using black silicon as a platform for different applications. 

Opponent: Professor Jan Linnros, Materials Physics, ICT School, Royal Institute of Technology, Sweden

Supervisor: Professor Harri Lipsanen, Aalto University School of Electrical Engineering, Department of Micro- and Nanosciences