Excitonic resonance spectra in qw and QD In0.3Ga0.7As/GaAs hetrostructures
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DOROGAN, Andrei; DOROGAN, Valerian; MEREUŢĂ, Alexandru; SYRBU, Alexei; SYRBU, Nicolae; VIERU, Tatiana; URSAKI, Veacheslav; ZALAMAI, Victor. Excitonic resonance spectra in qw and QD In0.3Ga0.7As/GaAs hetrostructures. In: Materials Science and Condensed Matter Physics. Editia a 6-a, 11-14 septembrie 2012, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2012, p. 198. ISBN 978-9975-66-290-1.
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Materials Science and Condensed Matter Physics
Editia a 6-a, 2012
Conferința "Materials Science and Condensed Matter Physics"
Chișinău, Moldova, 11-14 septembrie 2012

Excitonic resonance spectra in qw and QD In0.3Ga0.7As/GaAs hetrostructures


Pag. 198-198

Dorogan Andrei1, Dorogan Valerian1, Mereuţă Alexandru2, Syrbu Alexei2, Syrbu Nicolae1, Vieru Tatiana1, Ursaki Veacheslav3, Zalamai Victor3
 
1 Technical University of Moldova,
2 Swiss Federal Institute of Technology Lausanne,
3 Institute of Applied Physics
 
Disponibil în IBN: 23 martie 2020


Rezumat

The measurement of optical reflection and transmittance spectra had been carried out using MДР-2, JASCO-670 and СДЛ-1 spectrometers at 10K and 300K for S- and P-polarizations and different light angles incident on the In0,3Ga0,7As/GaAs heterostructure’s surface with quantum wells (QW). The samples’ cooling had been made in a optical cryogenic system of a locked cycle LTS-22-S-330 Workhorse. Lines conditioned by the hh,lh1-e1(1s,2s,3s), hh2,lh2 -e2(1s,2s,3s), hh1,lh1-e2(1s), and hh3,lh3,-e3(1s) transitions and particularities, conditioned by the quantum dots (QD) formed at the boundary of nanolayers and buffer layer, had been revealed in reflection, transmittance and luminescence spectra (fig. 1).figureFig.1. Reflection spectra shapes at 300 and 20K temperature measured experimentally (exp.) and calculated using the dispersion dependencies (cal.). The calculations of reflection and transmittance lines in a single oscillator model of Kramers – Kronig correlations and integrals showed, that the value of background dielectric constant near the (beginning) of transitions to ground and excited states of excitons are different for QW. The exciton binding energy hh-e1, lh1-e1, effective masses mhh * and mlh * and the damping factor had been determined for the optical transitions in QW and QD. The damping factor’s value is linked with the lifetime of charge carriers for the certain QD center or QW levels [1]. The damping factors for QD1QD4 and excitonic levels of QW do not essentially differ. The excitons’ emission lifetime in QD and of excitons in QW changes in the limits τо = (2Г0 )-1 0.04 -0.1ps for the studied sample. Financial supports from IRSES PVICOKEST – 269167 and STCU # 5402 projects are acknowledged.