Characterization of MgZnO epitaxial layers with high Mg concentration
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
In this work, a series of MgxZn1-xO epitaxial layers with different Mg mole fraction (x = 0.025; 0.166; 0.303; 0.318) grown by MBE has been investigated. Time-resolved photoluminescence (TRPL) measurements and scanning near field optical microscopy (SNOM) technique have been implemented in order to obtain PL spectra and decays as well as spatial distribution of the PL intensity and peak wavelength. Atomic force microscopy technique has been chosen to evaluate structural properties. Images of epitaxial layer surface profile, obtained by AFM technique, have revealed distinct characteristics for all samples and a strong surface roughness dependence on Mg concentration.
Analysis of the PL spectra has shown nonmonotonous PL peak wavelength dependence on temperature for three MgZnO samples with the highest Mg mole fraction. Arrhenius plots for the PL intensity dependence on temperature have been drawn and parameters have been evaluated. Samples with higher Mg mole fraction show higher value of activation energy. Time-resolved PL decays have revealed a biexponential shape for all four samples at low temperatures. Three samples with the highest Mg mole fraction show an increase of the PL decay time at low temperature. The PL intensity mappings, obtained by SNOM technique, have revealed considerable spatial variation of this parameter. Variation of the PL peak wavelength has been observed only for three samples with the highest Mg mole fraction.
Place, publisher, year, edition, pages
2011. , 32 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-90241OAI: oai:DiVA.org:kth-90241DiVA: diva2:504604
Subject / course
Microelectronics and Applied Physics
Master of Science in Engineering -Engineering Physics
Marcinkevicius, Saulius, Professor