Home > Seminars > Mid-UV Photodetectors and Emitters Grown on c-Al2O3 by Plasma-Assisted Molecular Beam Epitaxy

Mid-UV Photodetectors and Emitters Grown on c-Al2O3 by Plasma-Assisted Molecular Beam Epitaxy

Start:

5/23/2014 at 2:00PM

End:

5/23/2014 at 3:00PM

Location:

258 Fitzpatrick Hall

Host:

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Sergei Rouvimov

Sergei Rouvimov

VIEW FULL PROFILE Email: Sergei.Rouvimov.1@nd.edu
Phone: 574-631-0226
Office: 233 Stinson Remick Hall

Affiliations

Department of Electrical Engineering Research Associate Professor
College of Engineering Research Associate Professor
The research activities of Dr. Rouvimov are related to electron microscopy material science and nano-technology in collaboration with many research groups inside and outside of Notre Dame.  Currently electron microscopy is a key research technique for many bio, materials science and device ...
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The mid-UV optoelectronics (<300 nm) based on AlGaN QW heterostructures with a high Al-content is one of the most important application fields where plasma-assisted molecular-beam epitaxy (PA MBE) can demonstrate at least comparable results with other epitaxial technologies used for III-N device manufacturing. The presentation will address the growth conditions of (i) migration enhanced epitaxy of AlN nucleation layers with suppressed generation of threading dislocations (TD), (ii) (2-3)-µm-thick AlN buffer layers and AlGaN cladding layers with atomically smooth droplet-free morphology (rms<0.5nm) grown under the metal-rich conditions, using periodic modulations of either Al-flux or substrate temperature, respectively. Employing 3-nm-thick strained GaN insertions in the AlN buffer layers is shown to significantly decrease of TD density down to 108-109cm-2 in the top (active) MQW region. The specially designed QW structures with high Al-content (x≥0.8), grown pseudomorphically on a relaxed AlN buffer over c-Al203 will be demonstrated. These structures exhibit TE-polarized spontaneous (lasing) emission at a wavelength of 254(258) nm in contrast to TM-polarized emission observed in the relaxed SQW structures emitting at even larger wavelengths (~280 nm). The submonolayer digital epitaxy is demonstrated to fabricate AlGaN-based QWs by using the programmable closing the Al-cell shutter without any growth interruptions and change of the substrate temperature. These AlGaN-based QW structures demonstrate optically-pumped (excited by 4th or 5th harmonics of Nd-YAG laser) stimulated and laser emission within a spectral range of 258-303 nm with a minimum threshold excitation density of ~150kW/cm2 (for λ=289nm).

Seminar Speaker:

Valentin Jmerik

Valentin Jmerik

IOFFE Physical Technical Institute St. Petersburg, Russia

Dr. Jmerik is internationally known expert in PA MBE growth of semiconductor heterostructures with over 25 years of experience. He is currently affiliated with Centre of Nanoheterostructures Physics, at IOFFE Physical Technical Institute, focusing on wide-gap III-nitride semiconductors. He is involved in theoretical and experimental research of PA MBE of binary and alloyed compounds in the (AlGa)N system and related nanostructures for UV-optoelectronics applications.