Fabrication of Vertically Aligned Core-shell Nano Pillar Structure for High Sensitive Photonic Devices

<strong>Seminar of the School of Physical Sciences ----------------------------------------------</strong> Title: <strong>Fabrication of Vertically Aligned Core-shell Nano Pillar Structure for High Sensitive Photonic Devices</strong> Speaker: <strong>Dipak Paramanik</strong> (Iowa State University, Ames) Date: <strong>August 12, 2015</strong> <strong>Abstract: </strong>Semiconductor based photodetectors often employ p-i-n junction diodes for detection of photons. Traditional thin film type of structures are made of layers of p-type, i-type and n-type materials. In this type of geometry the photon has to travel through the entire top layer without being absorbed before it reaches the depletion region. This reduces the efficiency of the conversion process. If we can realize an idealized geometry of the p-i-n junction where the photons are directly incident on the depletion region then one can achieve higher quantum efficiencies. Such geometry will also allow us to locally probe, in real time, the charge carrier generation, transport and their interactions with defects in the depletion region. In this talk, I will describe clean room fabrication of vertically aligned GaN core-shell nano pillar structure over a large area for high sensitive photo detector applications. I will also describe fabrication and characterization of different types of solar cells including amorphous, heterojunction with intrinsic thin-layer (HIT) and tandem solar cells.