We are pleased to invite you to the IHPP PAS Seminar on Nitride Semiconductors. The next presentation will be held in a hybridmode – at the New Technologies seminar room, Al. Prymasa Tysiąclecia 98, and through Zoom platform (to get the link, please contact us at nitride_seminar@mail.unipress.waw.pl ).
The next seminar is scheduled on Monday 22.05.2023 at 14:00.
Speaker: prof. dr hab. Piotr Kossacki (University of Warsaw, Institute of Experimental Physics)
Title:Ultrafast dynamics of excitons in monolayers of semiconductor TMDs
Abstract: Monolayers of transition metal dichalcogenides (TMDs) draw a lot of attention as semiconducting materials with robust optical properties, strong Coulomb interaction and an optically accessible valley degree of freedom. Extraordinary properties of exciton complexes lead to new possibilities of exploration of nonlinear effects. In my seminar, I will focus on ultrafast studies of exciton dynamics explored by time resolved photoluminescence, FWM and femtosecond pump-probe experiments. The studies of neutral and charged exciton optical response show strong interactions between different complexes. For example creation of CX population in a given K,K’ valley leads to the capture of available free carriers in the opposite valley and reduces the interaction of neutral X with the Fermi sea. From the valley-resolved analysis of the observed effects we are also able to extract the spin-valley relaxation times of free carriers as a function of carrier density. The several effects related to interaction with carries such as the oscillator strength variation and energy shift will be discussed and compared to the cases of ordinary quantum wells. I will point similarities and differences in the complex landscape of exciton-exciton and exciton-carrier interactions in both two dimensional systems.
We are pleased to invite you to the IHPP PAS Seminar on Nitride Semiconductors. The next presentation will be held in a hybridmode – at the New Technologies seminar room, Al. Prymasa Tysiąclecia 98, and through Zoom platform (to get the link, please contact us at nitride_seminar@mail.unipress.waw.pl ).
The next seminar is scheduled on Monday 08.05.2023 at 14:00.
Speaker: prof. Michał Leszczyński (IHPP PAS, NL-12)
Title:Point defects in nitride semiconductors - do they really exist?
Presence of vacancies enables atoms to move. In the seminar, the following examples of experimental data will be given: i) diffusion of indium atoms in InGaN quantum wells that leads to well homogenization and decomposition, ii) diffusion of Al atoms smearing out the AlGaN/GaN interfaces, iii) diffusion of silicon and magnesium dopants. These data were obtained during annealing with and without gallium atoms in the gas above the samples, what had a significant influence on the diffusion.
We are pleased to invite you to the IHPP PAS Seminar on Nitride Semiconductors. The next presentation will be held in ain-personmode – at the New Technologies seminar room, Al. Prymasa Tysiąclecia 98, and through Zoom platform (to get the link, please contact us at nitride_seminar@mail.unipress.waw.pl ).
The next seminar is scheduled on Friday 28.04.2023 at 14:00.
Speaker: Prof. Leo Schowalter Founder (now retired) Crystal IS, Inc.; Visiting Professor, IMaSS,Nagoya University; Consultant, LJSchowalter LLC;
We are pleased to invite you to the IHPP PAS Seminar on Nitride Semiconductors. The next presentation will be held in a hybridmode – at the New Technologies seminar room, Al. Prymasa Tysiąclecia 98, and through Zoom platform (to get the link, please contact us at nitride_seminar@mail.unipress.waw.pl ).
The next seminar is scheduled on Monday 24.04.2023 at 14:00.
Speaker: dr hab. Małgorzata Wierzbowska, prof. IHPP PAS (IHPP PAS, NL-2)
Title:Perhaps "MB" can do for Unipress much more than "MD"
Unipress develops optoelectronic instruments and these devices should be theoretically designed with special care. Description of excitons, light and matter, including temperature and phonons, gets complicated due to the interactions of many fermions and bosons. The mathematical tools - second quantization, Green's functions, many-body (MB) perturbation theory - are difficult, even for theoreticians. The complexity of MB interactions exceeds that of the molecular dynamics (MD), which is not intended to describe the excited states with photons. The DFT either!
In this presentation, the existing modern developments for the interaction of light and matter will be reviewed, with the examples for photonic systems. We will also touch on a problem of device modelling - in an engineering way - with a special care for signal amplification and detection and existence of nonlinear optics in a quantum and "classical" manner. The maximal attention will be put to our intuition and making the presentation simple although comprehensive.
Thus it should be useful also for your future presentations!