Effects of a Si-doped InGaN Underlayer on the Optical Properties of InGaN/GaN Quantum Well Structures with Different Numbers of Quantum Wells
by
George Christian 1
, Menno Kappers 2, Fabien Massabuau 2, Colin Humphreys 2,3, Rachel Oliver 2 and Philip Dawson 1,*
George Christian 1, Menno Kappers 2, Fabien Massabuau 2, Colin Humphreys 2,3, Rachel Oliver 2 and Philip Dawson 1,*
1
School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL, UK
2
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK
3
School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
*
Author to whom correspondence should be addressed.
Materials 2018, 11(9), 1736; https://doi.org/10.3390/ma11091736
Received: 22 August 2018 / Revised: 5 September 2018 / Accepted: 14 September 2018 / Published: 15 September 2018
(This article belongs to the Special Issue III-Nitrides Semiconductor Research in the UK and Ireland)
In this paper we report on the optical properties of a series of InGaN polar quantum well structures where the number of wells was 1, 3, 5, 7, 10 and 15 and which were grown with the inclusion of an InGaN Si-doped underlayer. When the number of quantum wells is low then the room temperature internal quantum efficiency can be dominated by thermionic emission from the wells. This can occur because the radiative recombination rate in InGaN polar quantum wells can be low due to the built-in electric field across the quantum well which allows the thermionic emission process to compete effectively at room temperature limiting the internal quantum efficiency. In the structures that we discuss here, the radiative recombination rate is increased due to the effects of the Si-doped underlayer which reduces the electric field across the quantum wells. This results in the effect of thermionic emission being largely eliminated to such an extent that the internal quantum efficiency at room temperature is independent of the number of quantum wells.
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Keywords:
photoluminescence; InGaN; underlayer; quantum well; radiative lifetime
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MDPI and ACS Style
Christian, G.; Kappers, M.; Massabuau, F.; Humphreys, C.; Oliver, R.; Dawson, P. Effects of a Si-doped InGaN Underlayer on the Optical Properties of InGaN/GaN Quantum Well Structures with Different Numbers of Quantum Wells. Materials 2018, 11, 1736.
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