Functionalizing self-assembled GaN quantum dot superlattices by Eu-implantation

Magalhães, S.; Peres, M.; Fellmann, V.; Daudin, B.; Neves, A.J.; Alves, E.; Monteiro, T.; Lorenz, K.

doi:10.1063/1.3496624

Cited by 17 publications

(18 citation statements)

References 32 publications

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“…After HTHP annealing at 1400 ºC a significant decrease of the SL peak intensity is observed which can be due to intermixing but also due to the deterioration of the crystal quality such as the occurrence of phase separation. The as-implanted sample continues to show intense SL peaks confirming little effect of the implantation on the interface properties, however, all SL peaks are seen to shift to lower angles in agreement with previous implantation studies in SL samples 42 and attributed to the expansion of the c-lattice parameter typically observed in ion implanted III-nitrides due to hydrostatic strain introduced by implantation defects 38,41,43 . Very high implantation fluences, on the other hand, can lead to ballistic intermixing and a strong decrease of SL peaks 44 .…”

Section: Methodssupporting

confidence: 88%

Quantum well intermixing and radiation effects in InGaN/GaN multi quantum wells

Lorenz¹,

Redondo-Cubero²,

Lourenço³

et al. 2016

SPIE Proceedings

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Compositional grading of InGaN/GaN multi quantum wells (QWs) was proposed to mitigate polarization effects and Auger losses in InGaN-based light emitting diodes [K. P. O'Donnell et al., Phys. Status Solidi RRL 6 (2012) 49]. In this paper we are reviewing our recent attempts on achieving such gradient via quantum well intermixing. Annealing up to 1250 ºC resulted in negligible interdiffusion of QWs and barriers revealing a surprising thermal stability well above the typical MOCVD growth temperatures. For annealing at 1400 ºC results suggest a decomposition of the QWs in regions with high and low InN content. The defect formation upon nitrogen implantation was studied in detail. Despite strong dynamic annealing effects, which keep structural damage low, the created defects strongly quench the QW luminescence even for low implantation fluences. This degradation could not be reversed during thermal annealing and is hampering the use of implantation induced quantum well intermixing in InGaN/GaN structures.

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Section: Methodssupporting

confidence: 88%

Quantum well intermixing and radiation effects in InGaN/GaN multi quantum wells

Lorenz¹,

Redondo-Cubero²,

Lourenço³

et al. 2016

SPIE Proceedings

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“…22,23 GaN and AlN lms grown by hydride vapour phase epitaxy (HVPE) on c-plane sapphire were purchased from TDI Oxford instruments ($3 mm). All these samples were implanted simultaneously with two different uences: 1 Â 10 13 ions cm À2 and 1 Â 10 15 ions cm À2 , at the energy of 150 keV.…”

Section: Methodsmentioning

confidence: 99%

GaN:Pr³⁺ nanostructures for red solid state light emission

et al. 2014

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The photoluminescence of praseodymium implanted and annealed GaN films, quantum wells, nanowires and quantum dots was studied. After implantation and annealing, Pr 3+ intra-shell luminescence was achieved for all the analysed samples. In the trivalent charge state the ions' luminescence was found to be dominated by the red lines of the 3 P 0 / 3 F 2 transition. In the case of GaN films, an intense red emission is observed with the naked eye at room temperature. Photoluminescence excitation indicates that the preferential population mechanisms of this emission are achieved by using excitation above the GaN band gap. A correlation of the optically active ions' luminescence spectral shape and peak position in the different structures is established. For the GaN nanowires the 3 P 0 / 3 F 2 lines of the Pr 3+ ions are in good agreement with those identified in GaN films. In the case of GaN quantum dots, the ions' emission was found to be similar to that observed in AlN layers. For AlN/GaN/AlN quantum wells a similar behaviour was identified with the sharp ionic luminescence lines superimposed as a broad band, likely generated by the overlap of multiple Pr-centres. The ionic luminescence stability was analysed and discussed for all the studied samples.

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“…The as-grown sample #1110 was further submitted to thermal annealing treatments at 1200°C in flowing N 2 at 1 mbar pressure and placing a piece of AlN/sapphire face-to-face with the samples as a proximity cap to protect the surface during the high temperature treatment. The #987 and #989 GaN QD/AlN SL were implanted with high (1 × 10 14-15 ions cm -2 ) and low (1 × 10 13 ions cm -2 ) fluences of Europium ions; the SL structures were further submitted to post-implantation thermal annealing in order to achieve Eu 3+ optical activation [ 17 , 18 ].…”

Section: Methodsmentioning

confidence: 99%

Effect of Eu-implantation and annealing on the GaN quantum dots excitonic recombination

et al. 2011

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Undoped self-assembled GaN quantum dots (QD) stacked in superlattices (SL) with AlN spacer layers were submitted to thermal annealing treatments. Changes in the balance between the quantum confinement, strain state of the stacked heterostructures and quantum confined Stark effect lead to the observation of GaN QD excitonic recombination above and below the bulk GaN bandgap. In Eu-implanted SL structures, the GaN QD recombination was found to be dependent on the implantation fluence. For samples implanted with high fluence, a broad emission band at 2.7 eV was tentatively assigned to the emission of large blurred GaN QD present in the damage region of the implanted SL. This emission band is absent in the SL structures implanted with lower fluence and hence lower defect level. In both cases, high energy emission bands at approx. 3.9 eV suggest the presence of smaller dots for which the photoluminescence intensity was seen to be constant with increasing temperatures. Despite the fact that different deexcitation processes occur in undoped and Eu-implanted SL structures, the excitation population mechanisms were seen to be sample-independent. Two main absorption bands with maxima at approx. 4.1 and 4.7 to 4.9 eV are responsible for the population of the optically active centres in the SL samples.

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Functionalizing self-assembled GaN quantum dot superlattices by Eu-implantation

Cited by 17 publications

References 32 publications

Quantum well intermixing and radiation effects in InGaN/GaN multi quantum wells

Quantum well intermixing and radiation effects in InGaN/GaN multi quantum wells

GaN:Pr³⁺ nanostructures for red solid state light emission

Effect of Eu-implantation and annealing on the GaN quantum dots excitonic recombination

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Functionalizing self-assembled GaN quantum dot superlattices by Eu-implantation

Cited by 17 publications

References 32 publications

Quantum well intermixing and radiation effects in InGaN/GaN multi quantum wells

Quantum well intermixing and radiation effects in InGaN/GaN multi quantum wells

GaN:Pr3+ nanostructures for red solid state light emission

Effect of Eu-implantation and annealing on the GaN quantum dots excitonic recombination

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GaN:Pr³⁺ nanostructures for red solid state light emission