InGaN/GaN Structures: Effect of the Quantum Well Number on the Cathodoluminescent Properties

Abstract

In this work we compare luminescence results obtained on InGaN/GaN multiple quantum well (QW) structures with 10 and 30 QWs. The aim is to increase the intensity of faster blue QW emission and decrease the luminescence of the QW defect band, showing a slower luminescence decay time, which is undesired for fast scintillator applications. We demonstrate that increasing the number of InGaN QWs is an efficient method to reach this goal. The luminescence improvement of the sample with higher number of QWs is explained by the influence of the increased size of V‐pits with increased QW number. Thinner QWs on the side wall of V‐pits serve as barriers which separate carriers from dislocations penetrating through the V‐pit centre, supressing thus the non‐radiative and radiative recombination on defects. Based on cathodoluminescence (CL) results, the scintillator structure design is discussed. Scintillator structures with higher number of QWs can take advantage of both, improved luminescence efficiency and thicker active region.

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“…Materials with a very sharp scintillating response in the sub-1 ns regime have been previously studied (Padilha et al 2013, Turtos et al 2016a and they are found in the form of semiconductor nanoplatelets (Turtos et al 2016c) or multiple quantum well heterostructures (Hospodková et al 2017). In this case the quantum confinement of electron-hole pairs plays a significant role in enhancing the matrix element for the radiative transition (Wilkinson et al 2004) and it is also responsible for one of the most interesting features of scintillating nanocrystals: biexcitons with a very high binding energy and therefore stable at room temperature (Grim et al 2014).…”