Presentation
20 April 2017 Resonant tunneling diodes based on ZnO for quantum cascade structures (Conference Presentation)
Borislav Hinkov, Benedikt Schwarz, Andreas Harrer, Daniela Ristanic, Werner Schrenk, Maxime Hugues, Jean-Michel Chauveau, Gottfried Strasser
Author Affiliations +
Proceedings Volume 10123, Novel In-Plane Semiconductor Lasers XVI; 101231G (2017) https://doi.org/10.1117/12.2252753
Event: SPIE OPTO, 2017, San Francisco, California, United States
Abstract
The terahertz (THz) spectral range (lambda ~ 30µm – 300µm) is also known as the “THz-gap” because of the lack of compact semiconductor devices. Various real-world applications would strongly benefit from such sources like trace-gas spectroscopy or security-screening. A crucial step is the operation of THz-emitting lasers at room temperature. But this seems out of reach with current devices, of which GaAs-based quantum cascade lasers (QCLs) seem to be the most promising ones. They are limited by the parasitic, non-optical LO-phonon transitions (36meV in GaAs), being on the same order as the thermal energy at room temperature (kT = 26meV). This can be solved by using larger LO-phonon materials like ZnO (E_LO = 72meV). But to master the fabrication of ZnO-based QC structures, a high quality epitaxial growth is crucial followed by a well-controlled fabrication process including ZnO/ZnMgO etching. We use devices grown on m-plane ZnO-substrate by molecular beam epitaxy. They are patterned by reactive ion etching in a CH4-based chemistry (CH4:H2:Ar/30:3:3 sccm) into 50μm to 150μm square mesas. Resonant tunneling diode structures are investigated in this geometry and are presented including different barrier- and well-configurations. We extract contact resistances of 8e-5 Omega cm^2 for un-annealed Ti/Au contacts and an electron mobility of above 130cm^2/Vs, both in good agreement with literature. Proving that resonant electron tunneling can be achieved in ZnO is one of the crucial building blocks of a QCL. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 665107.
Conference Presentation
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Borislav Hinkov, Benedikt Schwarz, Andreas Harrer, Daniela Ristanic, Werner Schrenk, Maxime Hugues, Jean-Michel Chauveau, and Gottfried Strasser "Resonant tunneling diodes based on ZnO for quantum cascade structures (Conference Presentation)", Proc. SPIE 10123, Novel In-Plane Semiconductor Lasers XVI, 101231G (20 April 2017); https://doi.org/10.1117/12.2252753
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KEYWORDS
Zinc oxide

Diodes

Quantum cascade lasers

Etching

Gallium arsenide

Molecular beam epitaxy

Reactive ion etching

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