Quantum-confined Stark effect and mechanisms of its screening in InGaN/GaN light-emitting diodes with a tunnel junction

Pieniak, Katarzyna; Chlipała, Mikołaj; Turski, Henryk; Trzeciakowski, Witold; Muzioł, G.; Staszczak, G.; Kafar, Anna; Makarowa, Irina; Grzanka, Ewa; Grzanka, Szymon; Skierbiszewski, C.; Suski, T.

doi:10.1364/oe.415258

Cited by 24 publications

(16 citation statements)

References 41 publications

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“…Brecha et al showed that the piezoelectric polarization is present without excitation, even in QWs as thick as 25 nm [ 32 ]. On the other hand, Pieniak et al showed that the polarization field in such wide QW is fully screened under excitation [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

Dependence of InGaN Quantum Well Thickness on the Nature of Optical Transitions in LEDs

et al. 2021

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The design of the active region is one of the most crucial problems to address in light emitting devices (LEDs) based on III-nitride, due to the spatial separation of carriers by the built-in polarization. Here, we studied radiative transitions in InGaN-based LEDs with various quantum well (QW) thicknesses—2.6, 6.5, 7.8, 12, and 15 nm. In the case of the thinnest QW, we observed a typical effect of screening of the built-in field manifested with a blue shift of the electroluminescence spectrum at high current densities, whereas the LEDs with 6.5 and 7.8 nm QWs exhibited extremely high blue shift at low current densities accompanied by complex spectrum with multiple optical transitions. On the other hand, LEDs with the thickest QWs showed a stable, single-peak emission throughout the whole current density range. In order to obtain insight into the physical mechanisms behind this complex behavior, we performed self-consistent Schrodinger–Poisson simulations. We show that variation in the emission spectra between the samples is related to changes in the carrier density and differences in the magnitude of screening of the built-in field inside QWs. Moreover, we show that the excited states play a major role in carrier recombination for all QWs, apart from the thinnest one.

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Section: Introductionmentioning

confidence: 99%

Dependence of InGaN Quantum Well Thickness on the Nature of Optical Transitions in LEDs

et al. 2021

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“…The peak wavelength of 100 μm blue micro-LED appears a 6 nm blue shift as current density raised from 1 to 300 A/cm 2 , and 10 μm blue micro-LED, on the other hand, shows a blue shift of 5.7 nm. The blue shift would be attributed to the band filling effect and quantum-confined Stark effect [ 16 , 24 ]. The changes in photonic characteristics of blue micro-LEDs with different sizes are listed in Table 2 .…”

Section: Resultsmentioning

confidence: 99%

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

et al. 2023

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Colloidal CdSe/ZnS quantum dots (QD) enhanced micro-LEDs with sizes varying from 10 to 100 μm were fabricated and measured. The direct photolithography of quantum-dot-contained photoresists can place this color conversion layer on the top of an InGaN-based micro-LED and have a high throughput and semiconductor-grade precision. Both the uncoated and coated devices were characterized, and we determined that much higher brightness of a QD-enhanced micro-LED under the same current level was observed when compared to its AlGaInP counterpart. The color stability across the device sizes and injection currents were also examined. QD LEDs show low redshift of emission wavelength, which was recorded within 1 nm in some devices, with increasing current density from 1 to 300 A/cm2. On the other hand, the light conversion efficiency (LCE) of QD-enhanced micro-LEDs was detected to decrease under the high current density or when the device is small. The angular intensities of QD-enhanced micro-LEDs were measured and compared with blue devices. With the help of the black matrix and omnidirectional light emission of colloidal QD, we observed that the angular intensities of the red and blue colors are close to Lambertian distribution, which can lead to a low color shift in all angles. From our study, the QD-enhanced micro-LEDs can effectively increase the brightness, the color stability, and the angular color match, and thus play a promising role in future micro-display technology.

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“…3b that over a wide excitation power density range, the sample exhibits almost constant peak energy with increasing excitation power, i.e., an ultra-stable emission. In addition, the screening of QCSE always comes along with a narrowing of the linewidth 48 , 49 . Here, the lack of this behavior in the excitation power dependence of the full-width-half-maximum (FWHM) confirms once more that the QCSE in the InGaN QWs of Sample A is negligible.…”

Section: Resultsmentioning

confidence: 99%

InGaN micro-light-emitting diodes monolithically grown on Si: achieving ultra-stable operation through polarization and strain engineering

Xiao

Navid

et al. 2022

Light Sci Appl

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Micro or submicron scale light-emitting diodes (µLEDs) have been extensively studied recently as the next-generation display technology. It is desired that µLEDs exhibit high stability and efficiency, submicron pixel size, and potential monolithic integration with Si-based complementary metal-oxide-semiconductor (CMOS) electronics. Achieving such µLEDs, however, has remained a daunting challenge. The polar nature of III-nitrides causes severe wavelength/color instability with varying carrier concentrations in the active region. The etching-induced surface damages and poor material quality of high indium composition InGaN quantum wells (QWs) severely deteriorate the performance of µLEDs, particularly those emitting in the green/red wavelength. Here we report, for the first time, µLEDs grown directly on Si with submicron lateral dimensions. The µLEDs feature ultra-stable, bright green emission with negligible quantum-confined Stark effect (QCSE). Detailed elemental mapping and numerical calculations show that the QCSE is screened by introducing polarization doping in the active region, which consists of InGaN/AlGaN QWs surrounded by an AlGaN/GaN shell with a negative Al composition gradient along the c-axis. In comparison with conventional GaN barriers, AlGaN barriers are shown to effectively compensate for the tensile strain within the active region, which significantly reduces the strain distribution and results in enhanced indium incorporation without compromising the material quality. This study provides new insights and a viable path for the design, fabrication, and integration of high-performance µLEDs on Si for a broad range of applications in on-chip optical communication and emerging augmented reality/mixed reality devices, and so on.

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Quantum-confined Stark effect and mechanisms of its screening in InGaN/GaN light-emitting diodes with a tunnel junction

Cited by 24 publications

References 41 publications

Dependence of InGaN Quantum Well Thickness on the Nature of Optical Transitions in LEDs

Dependence of InGaN Quantum Well Thickness on the Nature of Optical Transitions in LEDs

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

InGaN micro-light-emitting diodes monolithically grown on Si: achieving ultra-stable operation through polarization and strain engineering

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