Photoluminescence studies of a perceived white light emission from a monolithic InGaN/GaN quantum well structure

Abstract

In this work we demonstrate by photoluminescence studies white light emission from a monolithic InGaN/GaN single quantum well structure grown by metal organic chemical vapour deposition. As-grown and thermally annealed samples at high temperature (1000 °C, 1100 °C and 1200 °C) and high pressure (1.1 GPa) were analysed by spectroscopic techniques, and the annealing effect on the photoluminescence is deeply explored. Under laser excitation of 3.8 eV at room temperature, the as-grown structure exhibits two main emission bands: a yellow band peaked at 2.14 eV and a blue band peaked at 2.8 eV resulting in white light perception. Interestingly, the stability of the white light is preserved after annealing at the lowest temperature (1000 °C), but suppressed for higher temperatures due to a deterioration of the blue quantum well emission. Moreover, the control of the yellow/blue bands intensity ratio, responsible for the white colour coordinate temperatures, could be achieved after annealing at 1000 °C. The room temperature white emission is studied as a function of incident power density, and the correlated colour temperature values are found to be in the warm white range: 3260–4000 K.

Eu-Doped AlGaN/GaN Superlattice-Based Diode Structure for Red Lighting: Excitation Mechanisms and Active Sites

“…We believe that this assignment is well-founded because PL measurements as a function of power excitation (BL blue-shifts by ∼50 meV for power densities from I 0 /10 up to I 0 , Figure S2) and temperature (Figure S3) agree well with the PL results of Reshckikov et al, indicating that the 2.8 eV band blue-shifts by increasing the excitation intensity, and that the corresponding thermal quenching begins at temperatures above 200 K. On the other hand, the broad YL band is peaked at ∼2.2 eV, for which the most accepted recombination models involve a DAP or free-to-bound (e-A) transitions. The YL typically involves deep defect levels in intrinsic GaN layers and is often reported as being related to the presence of the native defect V Ga and its complexes. , In addition, recent theoretical calculations suggest that the YL can also be caused by the carbon impurity (C N ) or its complex with oxygen (C N O N ). − Furthermore, it should be noticed that the YL is also affected if GaN is intentionally doped. Indeed a substantial increase of the YL intensity was found using several dopants such as Si or Mg, as reported by Reshckikov et al In Mg-doped GaN, first-principles calculations predicted the formation of three donor defects: a nitrogen vacancy, interstitial Mg, and the N-vacancy-Mg complex …”

Exploring swift-heavy ion irradiation of InGaN/GaN multiple quantum wells for green-emitters: the use of Raman and photoluminescence to assess the irradiation effects on the optical and structural properties

“…48 Nevertheless, given the complexity of the YB, the involvement of other kinds of defects for this emission cannot be excluded, particularly those involving V Ga and/or associated complexes. 27,28,[49][50][51] From Fig. 7b, it is noted that the InGaN excitonic emission peaks at 2.3 eV.…”

Effect of annealing temperature on luminescence properties of ZnWO 4 :Eu 3+ nanophosphor

“…The phosphor-converted white-light-emitting diodes (pc-WLEDs) are greatly considered as the fourth-generation light source due to their excellent properties such as good brightness, long lifetime, and high-energy efficiency [1][2][3][4][5]. Currently, commercial pc-WLEDs are usually based on the combination of a blue InGaN chip and a yellow phosphor Y 3 Al 5 O 12 :Ce 3+ (YAG: Ce), whose efficacies can be >80 lm/W for 1 W devices, higher than compact fluorescent lamps and comparable to linear fluorescent lamps [6][7][8][9]. However, YAG:Ce has a deficient red emission, leading to its bluish-cold light owing to its high-colour temperatures [correlated colour temperature (CCT) ≃7750 K] and low colour rendering index (≃70-80) [10,11].…”