Electroluminescence Mapping of InGaN-based LEDs by SNOM

Marutsuki, Giichi; Narukawa, Yukio; Mitani, Tomotsugu; Mukai, Takashi; Shinomiya, G.; Kaneta, Akio; Kawakami, Yoichi; Fujita, Sg.

doi:10.1002/1521-396x(200207)192:1<110::aid-pssa110>3.0.co;2-n

Cited by 9 publications

(6 citation statements)

References 19 publications

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“…Wide-band-gap GaN based quantum wells [1] are the essential part of many electro-optical devices, such as light-emitting-diodes (LEDs) or laser diodes, the precise nature of the light emitting process has not fully been understood due to the complex material physics and InGaN engineering involved. [2,3,4,5,6,7] A particular feature of InGaN photoluminescence (PL) is its tendency to slowly alter its PL emission, a phenomena that has been noticed by various authors [8,9,10,11,12,13,14] and often called "fatigue", "degradation" or with similar expressions.…”

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confidence: 99%

Transient memory effect in the photoluminescence of InGaN single quantum wells

et al. 2009

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The transition to maximum photoluminescence of InGaN single quantum wells is a phenomena that has time constants in the range of few seconds. Using a systematic illumination/darkening procedure we found that these characteristics are related to previous stimulations as if the sample has a memory of past illumination events. Choosing opportune time sequences, time constants were observed to vary more than 100%. These facts suggest the presence of carrier trapping/de-trapping processes that act beyond the single illumination event, accumulating over time in a complex effect.

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confidence: 99%

Transient memory effect in the photoluminescence of InGaN single quantum wells

et al. 2009

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“…As for the former, early work by A. Vertikov et al [22] suggested that strong carrier localisation in InGaN alloys might mitigate the adverse effects of dislocation on PL efficiency. G. Marutsuki et al [23] conducted a SNOM-EL mapping with a configuration illustrated in Figure 2 and found a correlation between regions of longer peak wavelength and stronger intensities, implying that injected carriers redistribute towards local potential minima. P.A.…”

Section: Quantum Wellsmentioning

confidence: 99%

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confidence: 99%

Optical Characterization of InGaN Quantum Structures at the Nanoscale

Fu,

Choi

2024

Adv Quantum Tech

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This review paper presents an overview of the optical characterization techniques for Indium Gallium Nitride (InGaN) quantum well (QW) structures at a nanoscale. The two major techniques are reviewed—Electron Microscopy‐Cathodoluminescence (EM‐CL) and Scanning Near‐field Optical Microscopy (SNOM). It elucidates the critical role these methodologies play in revealing the complex properties of InGaN QWs, including their structural characteristics, optical properties, carrier dynamics, and the effects of defects and doping. The review highlights key findings from a variety of studies, demonstrating how EM‐CL and SNOM have contributed to the understanding of these micro‐/nano‐ structures and their potential applications in high‐efficiency optoelectronic devices.

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“…3. Like the results of other groups [12], And the driving current redistribution caused by the indium fluctuation laterally has been proved experimentally [12].…”

Section: Electroluminescence Distribution Mappingsmentioning

confidence: 99%

“…With SNOM, the low temperature and room temperature optical properties of InGaN/GaN QW were studied [9,10,11]. Especially, recently, with SNOM and micro-spectroscopy method, the electroluminescence property of GaN/InGaN QW was studied [12,13]. It was found that the distribution of Indium in InGaN induced the redistribution of carriers.…”

Section: Introductionmentioning

confidence: 99%

High spatial resolution investigation of electroluminescence of InGaN/GaN multiple quantum wells by using scanning near-field optical microscopy and spectroscopy

2005

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The electro-luminescence (EL) properties of InGaN/GaN multiple quantum wells (MQWs) light emitting diodes (LEDs) with various emitting wavelength (purple, blue and green) were studied by scanning near-field optical microscope (SNOM). The high spatial resolution EL SNOM mappings and near-field spectra of the LEDs were acquired at various injection current conditions. The experiment shows that, though there are some common points, the EL properties of various LEDs are quite different. (i) The EL mappings show that the MQWs emission is spatially inhomogenous, which contain many islands like bright spots. (ii) The sizes of the bright spots are different ranging from 0.1 µ m to 1µm, the LED with longer emitting wavelength has larger bright spots. (iii) The injection current dependences of the shape of the bright spots of various LEDs are different. (iv) The emission wavelengths of brighter spots are longer in the same LED. (v)Increasing the injection current, the full widths at half maximum (FWHM) of the EL spectra grow larger. With the same injection current, the green LED has larger FWHMs than the blue and purple ones. (vi) Increasing the injection current, the blue shift of the green LED is obviously (~60 meV), but those of the blue one and purple are negligible. The phenomena above suggest that, the self-organized In-rich regions play a key role in the emission of all the InGaN/GaN MQWs LEDs, though they have different influences on the emission properties of the three LEDs with various emission wavelengths.One possible explanation is that, in the blue and purple LEDs, because the size of the In-rich areas are small, the quantum confined Stark effect caused by the piezoelectric field is negligible; but in the green LED, the In-rich areas are larger, the quantum confined Stark effect is obvious which caused the blue shift phenomenon. And in all LEDs, the band filling effect makes the FWHMs of the emission spectra larger. The results also show that SNOM is a powerful tool to study the local light emission properties at n anometer scale.

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Electroluminescence Mapping of InGaN-based LEDs by SNOM

Cited by 9 publications

References 19 publications

Transient memory effect in the photoluminescence of InGaN single quantum wells

Transient memory effect in the photoluminescence of InGaN single quantum wells

Optical Characterization of InGaN Quantum Structures at the Nanoscale

High spatial resolution investigation of electroluminescence of InGaN/GaN multiple quantum wells by using scanning near-field optical microscopy and spectroscopy

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