Research

– Post-doc (UT)

February 2017 – Current

My current research concerns smart interactive optics for lithography at extreme ultraviolet (EUV) wavelengths (project name: SMILE). We fabricate piezoelectric thin films and actuators, and study the underlying physics to incorporate them in the EUV multilayer mirrors in order to perform wavefront corrections. For this work, I have direct contact and collaboration with the partners at Carl ZEISS SMT and Solmates B. V.

Read more details about the SMILE project in this page.

 

– Post-doc (NTNU)

October 2014 – January 2017

In this position, I studied potential intermediate band solar cells (IBSCs). In particular, I worked on fabrication and characterization of deep level intermediate band materials, namely doped ZnS and Si and Cu2O. I also studied reduced MoO3 containing oxygen vacancy defects resulting in formation of energy levels/state within the band-gap. My contributions were pulsed laser deposition of thin films, pulsed laser melting of implanted semiconductors, fabrication of solar cell devices, and characterization of thin films and solar cell devices using various relevant techniques. The outcomes of the research were published in multiple conferences and over seven journal papers.

My duties also include assisting in the training and supervision of PhD and final year project or master students.

In addition to the research activities, I have been the course coordinator and the lecturer for the master level course “Energy and Environmental Physics” at NTNU.

 

– Visiting Scholar (IES-UPM)

March 2016 – July 2016 (5 months)

During the research visit, I joined the group of Prof. Antonio Martí, the inventor of intermediate band solar cells, at the Solar Energy Institute of the Technical University of Madrid. We investigated the voltage preservation and the two-photon effect in the solar cells that I fabricated at NTNU earlier in 2016. The outcomes were published in Sol. Energy Mater Sol. Cells journal.

 

Mohammadreza_nematollahi_PLD_NTNU
Photo by Geir Mogen/NTNU

– PhD (NTNU)

October 2010 – October 2014 (4 years)

Title: Cr-doped ZnS for Intermediate Band Solar Cells  (download abstract)

Trial lecture title: Highly mismatched alloys for optoelectronics. (see the slides here)

 

Pulsed laser deposition of ZnS and transition metal doped ZnS:

(a) The rectangular ablated area on the target showing the X and Y scanning directions. (b) Image of the target, and the visible plasma plume. (c) The film after ablation still on the heater. (d) RHEED pattern of the Si substrate just before the deposition and (e) ZnS film after the deposition.
(a) The rectangular ablated area on the target showing the X and Y scanning directions. (b) Image of the target, and the visible plasma plume. (c) The film after ablation still on the heater. (d) RHEED pattern of the Si substrate just before the deposition and (e) ZnS film after the deposition.
Cross-section SEM image of a single hetero-junction cell with ZnS. The top layer is the Au/Al contact
Cross-section SEM image of a single hetero-junction cell with ZnS. The top layer is the Au/Al contact
Schematic structure of the solar cells studied. (a) A single hetero-junction cell with Cr:ZnS, and (b) with ZnS. (c) A double hetero-junction cell with Cr:ZnS, and (d) with ZnS.
Schematic structure of the solar cells studied. (a) A single hetero-junction cell with Cr-doped ZnS, and (b) with ZnS. (c) A double hetero-junction cell with Cr-doped ZnS, and (d) with ZnS.

 

– MSc (SUT)

September 2007 – February 2010

Title: The effect of metal oxides on gasochromic properties of WO3 thin films formed by pulsed laser deposition (download abstract)

Supervisor: Prof. Seyed Mohammad Mahdavi

Gasochromic schematic
The optical properties of the gasochromic film changes when exposed to dilute H2 gas. The process is reversible by introducing O2 gas.

 

gas test schematic
Schematic of the gas test experiment.

 

Gasochromic films under dilute H2 gas. The color difference is caused by varying the film concentration.
Gasochromic films under dilute H2 gas. The color difference is due to the presence of Ti, Mo, and Ni cations in the WO3 films.