Welcome 

.My last name is Pristovsek, I am the head and the only permanent member of the international section. Since almost nobody pronounce my name correctly on first try, just call me Markus.

Light onto the black art of semiconductor formation

In recent years the growth of nitrides for LEDs used in solid state lightning, laser diodes, and ultra-violett diodes for water purification and air disinfection became challenging not only from an academic point of view but with a several billion heavy industrial perspective. The workhorse for production of the layer structures is the so-called metal-organic vapour phase epitaxy (MOVPE). Now even politicians come to start up a new MOVPE lab:The photo shows me (to the left) with the then British Science Minister David Willets at the opening of the new 6×2 MOVPE reactor at the Cavendish laboratory of Cambridge University in 2013.
Due to the importance of GaN, large efforts are devoted worldwide into research of nitride semiconductor growth and device development. Even though, growth by MOVPE is done in hundreds of laboratories and factories worldwide, it is not very well understood. Brute force optimisation lead to the nanostructures used in current devices (which are often less than 10 atoms in height). Further progress needs finer control of unwanted defects (like carbon, or missing atoms) in a 1/billion level.
As a small university group, it is important to try approaches not possible in an industrial environment. Hence, we focus on new materials or orientations to enable new electronic or optical devices.
A big task is easier with collaboration. We are very closely related to the Amano-lab. We have had a lot of international visiting students from France, from Italy, and from Germany, and we collaborate with groups in Germany, Singapore, and Ireland.

About myself

From 1989 I studied basic physics at the Technical University of Berlin. In 1995 I obtained my Diploma at Prof. Richter’s Group about Growth and Passivation of III-V-Semiconductors. The group was the leading group to build and use Reflectance Anisotropy Spectroscopy (RAS) to study classical III-V semiconductor growth in metal-organic vapor phase epitaxy, the workhorse of III-V semiconductor nanostructure growth. I did my PhD also in the same group in 2000.
The in-situ monitoring research was quite successful and led to the foundation of the company LayTec which is still thriving today. Not least because nitride semiconductor growth requires good in-situ monitoring for success.
In 2000 just after I got my PhD, I did not join LayTec but I went to Tsukuba, Japan. There I worked as a Postdoc at the National Institute for Materials Science on in-situ characterisation with RAS but also with in-situ Scanning Tunneling Microscopy (STM). The latter allows in principle to follow single atoms on the surface. Back in Berlin, after a short stay at the Ferdinand-Braun-Institut für Höchstfrequenztechnik I joined again the TU Berlin where I led the MOVPE activities. New materials such as InN and novel ferromagnetic semiconductors like InAsP:Mn with a tailorable Mn acceptor depth were investigated, with the main focus on the growth process. A very special result was the first and only in-situ STM for MOVPE. This has been the only STM worldwide that could operate at 700°C at near atmospheric pressure. Other innovative tools were the only multi-channel RAS setup for semiconductor epitaxy, and three spectroscopic ellipsometers for during growth studies. These were put to use to measure unknown refractive indices at high temperature, to study surfaces (especially of nitride semiconductors), and to learn about the relaxation of In containing alloys.
Over the years my focus also changed towards III-nitride semiconductors. Being driven by industrial application, there are still many open questions. After nearly ten years in Berlin, I joined the GaN center at Cambridge University (UK) in 2012. The research focus there was industrial viable long wavelength InGaN LEDs. First using the (11-22) orientation, which is called semi-polar, because it is between the polar (0001) and the non-polar (1-100) orientation. Polar refers to the internal polarisation, which arises from a charge transfer between the alternating nitrogen and metal atomic layers. Since the LEDs did not show the expected performance, I delved into finding out why.
Even though in 2017 I became Professor at Nagoya University, this question still follows me. However, there are other possible valuable ideas left aside in the rush for device applications and products, which is so characteristic for the Nitrides. Since progress of main application has slowed, the sideways may hold the important answers for the future.
You can also check my profile page at NU which also contains recent talks and literature lists.