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Al(Ga)N/GaN nanostructures for intersubband optoelectronics in the near- and mid-infrared

Abstract : This work reports on the design, epitaxial growth and characterization of Al(Ga)N/GaN quantum wells (QWs) and quantum dots (QDs) which constitute the active region of intersubband (ISB) devices operating in the near-infrared (NIR) and mid-infrared (MIR) spectral regions. Growth of these structures was performed using molecular beam epitaxy. The deposition process required fine tuning due to the large lattice mismatch. Infrared optical characterization demonstrates that the polarization-induced internal electric fields introduces a blue shift of the transitions and can critically modify the absorption magnitude. Three-dimensionally confined GaN/AlN QDs introduces many novel properties for application as active region in ISB devices. The growth of QDs was performed under both Ga-rich and N-rich conditions. Dilution of QDs with required size was achieved using the enhanced-mobility condition of the Ga-rich method. Spectroscopic studies reveal absence of non-radiative recombination even in long lived QDs. Photodetectors fabricated on GaN/AlN QD superlattices present photocurrent at NIR and MIR, assigned to s-pz and s-pxy transitions, respectively. The dark current depends on the QD density due to hopping transport. Foreseeing the importance of ISB devices in MIR and far-infrared regions of the spectrum, we have achieved ISB wavelength extension up to ~ 10 µm. This was performed basically by decreasing the internal electric-field and reducing the quantum confinement in GaN/AlGaN QW superlattices. Doping can induce a blue shift of more than 50% of the ISB transition energy, due to many-body effects.
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https://tel.archives-ouvertes.fr/tel-00517495
Contributor : Prem Kumar Kandaswamy Connect in order to contact the contributor
Submitted on : Tuesday, September 14, 2010 - 4:58:18 PM
Last modification on : Tuesday, May 11, 2021 - 11:36:06 AM
Long-term archiving on: : Wednesday, December 15, 2010 - 2:51:43 AM

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Prem Kumar Kandaswamy. Al(Ga)N/GaN nanostructures for intersubband optoelectronics in the near- and mid-infrared. Condensed Matter [cond-mat]. Université de Grenoble, 2010. English. ⟨tel-00517495⟩

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