Career

# CV

You can download my English CV here (pdf, 115 kB). Version as of Aug 3rd, 2012.
Można pobrać moje CV tutaj po polsku (pdf, 1,25 MiB). Wersja z 12.09.2012.

# Overview

[sections in development]
I am a fifth year master's degree student and work under prof. Stępniewski (his homepage). Our research group primarily focus on an innovative method of producing graphene. Secodarily, we work on AlGaN heterostructures, see Nitrides Nanostructures Laboratory webpage (in Polish).

#### Why is graphene so interesting?

Graphene is a two dimensional crystal of carbon atoms situated in honeycomb pattern.
Basically, in a solid optical and electrical properties are determined by electrons just below Fermi level, which are the only free ones to react to small change of circumstances. So peculiarly, because of this particular crystal constraints, those electrons behave as if they were massless (or more formally, their effective mass $m_*$ is zero). This makes them extremely fast even in weak electric fields (they have high mobility). Further, graphene properties may be changed from default semi-metallic to insulating or metallic by proper shaping of its boundary. This rises expectations of making transistors from this material only. More still, graphene may become basis to production of nanotubes, which are very interesting objects, eg. it is reported that they are 50-100 times stronger than steel. The very first nanotube transistor, made by IBM, was already working at 100 GHz, that is about 30 times faster than conventional silicon ones.

Graphene has numerous potential implemantations. For instance, you may be interested to see page 4 here (in Polish).

#### Short story of graphene history:

[To be rewritten to include research on 'single-layer graphite' before 2004]
It was first considered as crystallographic possibility as soon as late 1940's, when it's electronic structure was calculated as an exercise before moving to more natural 3D crystals. Indeed, the results showed that it could not exist in isolated form because it would curl up. So it was forgotten for half a century until in 2004 Andre Geim and Konstantin Novoselov glued some Scotch tape to a lump of carbon, peeled it off and after repeating many times they got tiny (few tens of microns across) flakes of graphene. Being glued to substrate, it couldn't roll; yet those forces were small enough not to distract the original electronic structure. The 2D behavior was confirmed by solid spectroscopic evidence. This sparked a whole new field of studies, which has already grown into thousands of researchers all around the world. For this discovery, Geim and Novoselov were awarded Nobel Prize in physics in 2010 - which is pretty soon for this prize. The astonishing simplicity of this experiment makes it one of the most spectacular scientific peculiarity of whole last decade (the other being the levitating frog, see it on YouTube).

#### What am I doing?

I used to treat graphene samples with Raman spectroscopy. However, for my master's thesis I went to magnetotransport.

I put samples into Variable Temperature Insert (VTI), set for demanded temperature (I work with 65 down to 2 K) and then scan through magnetic field $\vec{B}$ from +12 to -12 T. Each point is spaced by 0.1 T and consists of measuring 4 voltages, which give information on longitudal and transversal (Hall) resistance, $R_{xx}$ and $R_{xy}$. I easily see Shubnikov - de Haas oscillations in $R_{xx}$ and quantum Hall effect (plateaus) in $R_{xy}$. From these effects I am yet to calculate useful information, such as concentration and sign of primary and secondary carriers (i.e. how many electrons and holes there are in that particular sample).

[about to insert here a picture]

# Publications and work

Reviewed:

• (05.2011) My only (yet) publication references:
• K. Zieleniewski, K. Pakuła, R. Bożek, K. Masztalerz, A. Wysmołek, and R. Stępniewski
“Built-In Electric Field in High Quality GaN/AlGaN Quantum Wells”
(Wbudowane pole elektryczne w wysokiej jakości studniach kwantowych GaN/AlGaN)
ACTA PHYSICA POLONICA A, 119, 657-659 (2011)
• Link to online color version (pdf, 1 MB).

Non-reviewed:

• (08.2012) Skrypt z mechaniki kwantowej z wykładu na obozie letnim Almukantaratu w Załęczu — tutaj.
• (08.2012) My Offtopicarium talk on nuclear bomb summary — here.
• (04.2010) Moja prezentacja o elektroodbiciu (seminarium, IV rok) pod kierunkiem Anety Drabińskiej — tutaj (pdf, 2,3 MB).
• (11.2009) Moja prezentacja o mikroskopie sił atomowych (seminarium, IV rok) pod kierunkiem Rafała Bożka — tutaj (pdf, 7 MB).
• (08.2007) Presentation for summer schools What planets do we have?here (ppt, 0,8 MB).
• (06.2005) Prezentacja na zielone szkoły Jak szukać gwiazd?tutaj (ppt, 1,4 MB). Razem z Igorem Wójcikowskim.
• Presentation for summer schools How to find stars in the sky?here (ppt, 1,4 MB). Made with Igor Wójcikowski.
• (07.2004) Referat na mój drugi obóz Almukantaratu o spektroskopiitutaj (doc, 41 kB).
wersja strony: 49, ostatnia edycja: 16 Dec 2014 21:00
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