Strain and size combined effects on the GaN band structure: VEELS and DFT study.
A nanoscale study of combined strain/size effects has been performed using monochromated valence electron energy-loss spectroscopy and density functional theory (DFT) calculations to locally explore the valence and conduction bands of a strained 2 nm GaN quantum well inserted between two fully relaxed AlN thick layers. Two main electronic transitions from the valence to the conduction band were experimentally detected and interpreted. The first transition was shown to be a collective oscillation (or plasmon), which was significantly blue-shifted in energy mainly due to the widening of the valence-band top-part. The second, however, had a single-particle character, that is: Ga-3d → Ga-4p, and was weakly affected by strain and size. In addition, our DFT calculations showed that strain and size can be adjusted separately to tune the GaN band-gap energy.
LMPHE, URAC-12, Faculty of Sciences, Mohammed-V University, 10000 Rabat, Morocco. benaissa.um5@gmail.com benaissa@fsr.ac.ma.
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http://orcid.org/0000-0003-4460-0844
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Benaissa
Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany.
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Sigle
LMPHE, URAC-12, Faculty of Sciences, Mohammed-V University, 10000 Rabat, Morocco. benaissa.um5@gmail.com benaissa@fsr.ac.ma.
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Zaari
LMPHE, URAC-12, Faculty of Sciences, Mohammed-V University, 10000 Rabat, Morocco. benaissa.um5@gmail.com benaissa@fsr.ac.ma.
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Tadout
Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany.
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van Aken