Internal quantum efficiency of AlGaN/AlN quantum dot superlattices for electron-pumped ultraviolet sources

Nanotechnology
A HarikumarE Monroy

Abstract

In this paper, we describe the growth and characterization of ≈ 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (0 ≤ x ≤ 0.1) Stranski-Krastanov quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>1011cm-2) quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission efficiency remains constant for acceleration voltages below ≈ 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The internal quantum efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions...Continue Reading

References

Jun 13, 1988·Physical Review Letters·G Bastard
Jun 27, 2017·Reports on Progress in Physics·Theodore D Moustakas, Roberto Paiella

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