We describe the theoretical and experimental studies of GaN/AlGaN based resonant tunnelling diodes, and in particular analyse the effects and typical values of interface roughness, and then discuss the implications of these, realistic material quality parameters on performance of unipolar optoelectronic devices

Cooper, JD

Edmunds, C

Gardner, G

Grier, A

Harrison, P

Ikonic, Z

Indjin, D

Malis, O

Mantra, MJ

Shao, J

Valavanis, A

White Rose Research Online

Design considerations for GaN/AlN based unipolar (opto-)electronic devices, and interface quality aspects

This is a repository copy of Design considerations for GaN/AlN based unipolar (opto-)electronic devices, and interface quality aspects.White Rose Research Online URL for this paper:http://eprints.whiterose.ac.uk/106549/Version: Accepted VersionProceedings Paper:Grier, A, Valavanis, A, Edmunds, C et al. (8 more authors) (2016) Design considerations for GaN/AlN based unipolar (opto-)electronic devices, and interface quality aspects. In: 2016 IEEE Photonics Society Summer Topical Meeting Series. 2016 IEEE Photonics Society Summer Topical Meeting (SUM 2016), 11-13 Jul 2016, Newport Beach, CA, USA. IEEE , pp. 90-91. ISBN 9781509019007 https://doi.org/10.1109/PHOSST.2016.7548743© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.eprints@whiterose.ac.ukhttps://eprints.whiterose.ac.uk/Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Design considerations for GaN/AlN based unipolar (opto-)electronic devices, and interface quality aspects  A. Grier,1 A. Valavanis,1 C. Edmunds,2 J. Shao,2 J. D. Cooper,1 G. Gardner,3,4 M. J. Manfra,2,3,4,5 O. Malis,2 D. Indjin,1 Z. Ikonić,1 and P. Harrison6  1Institute of Microwaves and Photonics, School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom 2Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA 3Birck Nanotechnology Center, West Lafayette, Indiana 47907, USA 4School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA 5School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA 6Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB, United Kingdom  Abstract: We describe the theoretical and experimental studies of GaN/AlGaN based resonant tunnelling diodes, and in particular analyse the effects and typical values of interface roughness, and then discuss the implications of these, realistic material quality parameters on performance of unipolar optoelectronic devices.   The AlGaN/GaN material system has been proposed as a highly promising alternative to more conventional III–V systems from the perspective of various optoelectronic devices, including quantum cascade lasers operating from mid-infrared to THz range, photodetectors and electronic devices like resonant tunnelling diodes. In the longer wavelength range the high LO-phonon energy (92 meV) in GaN is expected to significantly reduce the thermal degradation effects, coming from non-radiative phonon-assisted transitions between active laser states, which could potentially allow laser emission at higher THz frequencies, and also higher temperature operation [1]. In the shorter, mid-infrared range, the high conduction band offset between AlN and GaN (~2 eV) can be exploited to comfortably confine subbands with separations required for laser emission at 1.55 たm [2], and could additionally reduce leakage currents, enabling high temperature operation. However, while electroluminescence has been demonstrated, there seems to be a lack of a successful demonstration of lasing in these devices. An accurate description and detailed understanding of electron transport in AlGaN/GaN heterostructures is critical for optimizing their performance, and ultimately realizing high-quality optoelectronic devices. Resonant tunnelling diodes (RTDs) are interesting devices in their own right, and also the simplest devices in which vertical tunneling and scattering transport can be extensively investigated, both experimentally and theoretically: the experience might then be transferred to the design of more complicated, optoelectronic devices. With these aims we have investigated electron transport in epitaxially grown nitride-based resonant tunneling diodes (RTDs), as well as in superlattice-type sequential tunneling devices [3]. The density-matrix model was developed, and shown to be able to reproduce the experimentally measured current–voltage characteristics, with the dephasing terms in the model calculated from semi-classical scattering rates. Scattering-induced broadening effects are found to have a significant influence on the predicted / experimental performance. In particular, the interface roughness parameters have a very strong influence on current magnitude, peak-to-valley ratios and misalignment features, up to the extent of being able to destroy the negative differential resistance in RTDs. Furthermore, the characteristics of sequential tunneling devices are dominated by a parasitic current, most likely caused by dislocations. Overall, an excellent agreement between the simulated and experimentally measured tunneling current-bias dependence is demonstrated. The analysis of the scattering effects, contact doping and growth quality on electron transport highlights critical optimization parameters for the development of III–nitride unipolar electronic and optoelectronic devices.  Investigation of AlGaN quantum cascade laser structures, also performed by the density matrix method, shows that a realistic level of interface roughness will significantly degrade the gain and useful operating temperature of some previous designs [4]. These can be improved by a structure optimization, based on a genetic algorithm [4], however it is likely that further improvements of the material quality are essential for the III-nitride optoelectronic devices to demonstrate their full potential. Acknowledgement: The authors are grateful to EPSRC (UK) for a DTG award and to the University of Leeds FIRC 2011 grant. Experimental work was supported by the NSF Award No. ECCS-1001431 and from the Defense Advanced Research Project Agency (DARPA) under Contract No. D11PC20027. References: [1] E. Bellotti, K. Driscoll, T. D. Moustakas, and R. Paiella, “Monte Carlo study of GaN versus GaAs terahertz quantum cascade structures,” Appl. Phys. Lett., 92, 101112 (2008). [2] V. D. Jovanović, Z. Ikonić, D. Indjin, P. Harrison, and R. A. Soref, “Designs for そ=1.55 たm GaN-based intersubband laser active region,” Japan. J. Appl. Phys., 43, 7444, 2004. [3] A. Grier, A. Valavanis, C. Edmunds, J. Shao, J. D. Cooper, G. Gardner, M. J. Manfra, O. Malis, D. Indjin, Z. Ikonić, and P. Harrison, “Coherent vertical electron transport and interface roughness effects in AlGaN/GaN intersubband devices”, J. Appl. Phys, 118, 224308 (2015). [4] A. Grier, “Modelling the optical and electronic transport properties of AlGaAs and AlGaN intersubband devices and optimisation of quantum cascade laser active regions”, PhD Thesis, University of Leeds, 2015. 

A. Grier

A. Valavanis

C. Edmunds

J. Shao

J. D. Cooper

G. Gardner

M. J. Mantra

O. Malis

D. Indjin

Z. Ikonic

P. Harrison

Crossref

http://eprints.whiterose.ac.uk/106549/1/SummerTopicals2016-abstract-Ikonic-contributed.pdf

Design considerations for GaN/AlN based unipolar (opto-)electronic devices, and interface quality aspects

Abstract

Similar works

Full text

Available Versions

White Rose Research Online

White Rose Research Online

Crossref