Abstract-Pseudo-square AlGaN/GaN quantum wells for terahertz absorption

M. Beeler^1,2, C. Bougerol^1,3, E. Bellet-Amalric^1,2 and E. Monroy^1,2

1 Université Grenoble Alpes, 38000 Grenoble, France
2 CEA-Grenoble, INAC/SP2M/NPSC, 17 avenue des Martyrs, 38054 Grenoble, France
3 Institut Néel-CNRS, 25 avenue des Martyrs, 38042 Grenoble Cedex 9, France
Appl. Phys. Lett. 105, 131106 (2014); http://dx.doi.org/10.1063/1.4896768

http://scitation.aip.org/content/aip/journal/apl/105/13/10.1063/1.4896768

THz intersubband transitions are reported down to 160 μm within AlGaN/GaN heterostructures following a 4-layer quantum well design. In such a geometry, the compensation of the polarization-induced internal electric field is obtained through creating a gradual increase inpolarization field throughout the quantum “trough” generated by three low-Al-content layers. The intersubband transitions show tunable absorption with respect to doping level as well as geometrical variations which can be regulated from 53 to 160 μm. They also exhibit tunnel-friendly designs which can be easily integrated into existing intersubband device architectures

Abstract-Terahertz absorbing AlGaN/GaN multi-quantum-wells: Demonstration of a robust 4-layer design

M. Beeler¹, C. Bougerol², E. Bellet-Amalric¹, and E. Monroy¹

¹CEA-CNRS Group “Nanophysique et semiconducteurs,” INAC-SP2M, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
²CEA-CNRS Group “Nanophysique et Semiconducteurs,” Institut Néel-CNRS, 25 rue des Martyrs, 38042 Grenoble Cedex 9, France

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http://apl.aip.org/resource/1/applab/v103/i9/p091108_s1?isAuthorized=no
We report on AlGaN/GaN multi-quantum-well structures displaying intersubband absorption in the THz spectral range. First, we theoretically analyze the weaknesses of the state-of-the-art GaN-based step-quantum-well architecture from an optoelectronic standpoint. We then propose a modified geometry with improved structural robustness considering the uncertainties associated to the growth. This later structure, consisting of 4-layer quantum wells, has been grown by plasma-assisted molecular-beam epitaxy and characterized structurally and optically. Low temperature absorption of samples with different Si doping levels confirms intersubband transitions in the far-infrared, centred at 28 μm.