Seminars in Photonics

Micro and Nanoscale Materials Design, Production and Structuring for
Photonics Devices

Dr. Tahir Çolakoğlu
Center for Solar Energy Research and Applications (GÜNAM), Middle East
Technical University, Ankara, Turkey

Abstract:

I will present the promising results and findings of my experimental
research studies in the field of Micro and Nanophotonics. The talk will
cover the advanced material and device design studies for IR imaging and
solar cell applications. In addition, the implementation of pulsed lasers to
create functional photonic devices inside Si will be discussed.
Quantum well infrared photodetector (QWIP) is still the only field proven
low-cost long-wavelength infrared photon sensor. An impressively high
quantum efficiency of 31% in the pixels of a large format, grating-coupled
InP/In0.48Ga0.52As QWIP focal plane array (FPA) was attained. The results
clearly point out that the main drawbacks of the standard QWIP technology
can be overcome through the utilization of alternative material systems and
improved FPA processing techniques.
Previous attempts for 3D laser microfabrication of Si were impeded. In this
study, it was realized by invoking nonlinear feedback mechanisms arising
from interaction of infrared laser pulses with Si to create self-organised
superstructures directly at any selected position deep inside Si.
Furthermore, a novel selective etching procedure for laser modified Si
regions was developed to produce promising devices. We demonstrate the first
“in-chip” phase-holograms, lenses and gratings, multilevel, erasable
information storage, embedded microfluidic channels for cooling of
microchips, through-Si vias, slicing of a wafer into microns-thick plates
for low-cost Si photovoltaics.
Si nanowire-AgInSe2 thin film heterojunctions were produced successfully. It
was demonstrated that the resulting device architect significantly improved
the photosensitivity of the heterojunction diode compared to the planar
reference.

@ Science Faculty, Chemistry Dept., Seminar Room
Date:  October 21, 2016
Time: 14:30