Article
Materials Science, Multidisciplinary
Jens W. Tomm, Artem Bercha, Grzegorz Muziol, Joachim Piprek, Witold Trzeciakowski
Summary: The analysis of photoluminescence in polar light emitting diode (LED) structures with a 25 nm In0.17Ga0.83N quantum well reveals that the observed emission is likely from a set of closely spaced excited states. The ground state decays very slowly and accumulates long-living charge. However, this charge accumulation can be quantified spectroscopically using short reverse voltage pulses. The emission from excited states is effective and exhibits exponential decay with time constants of 1.5 ns and 8 ns at 6 K and 300 K, respectively, indicating dominance by radiative processes. These findings suggest a potential pathway for improved polar device architectures.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Shouqiang Lai, Chaohsu Lai, Saijun Li, Guolong Chen, Xi Zheng, Tingwei Lu, Zongming Lin, Rongxing Wu, Yijun Lu, Hao-Chung Kuo, Zhong Chen, Tingzhu Wu
Summary: In this study, the temperature-dependent photoluminescence characteristics of green InGaN/GaN multiple quantum wells (MQWs) with InGaN/GaN pre-wells and InGaN pre-layers were investigated, and the electroluminescence properties of the corresponding mini-LEDs were studied. The fitting results of the temperature-dependent photoluminescence spectra using the Vaishini and Arrhenius models showed that the S-shaped temperature-dependent peak energies of green InGaN/GaN MQWs grown on pre-wells and pre-layers originated from localized states, and better crystal quality was observed in the MQWs with pre-layers. Moreover, the electroluminescence properties of green mini-LEDs were compared, demonstrating the advantages of growing green MQWs with an InGaN prelayer.
IEEE ELECTRON DEVICE LETTERS
(2023)
Review
Physics, Applied
D. J. Binks, P. Dawson, R. A. Oliver, D. J. Wallis
Summary: LEDs based on hexagonal InGaN/GaN quantum wells are widely used for lighting applications, but their performance is limited for green and amber emission and at high drive currents. Growing quantum wells in the cubic phase is a promising alternative due to its reduced bandgap and absence of strong polarization fields. The major structural defects in cubic GaN are stacking faults, which affect the optical properties and can propagate into active layers.
APPLIED PHYSICS REVIEWS
(2022)
Article
Physics, Applied
Satoshi Kurai, Junji Gao, Ryoga Makio, Naoya Hayashi, Shota Yuasa, Ryutaro Yamamoto, Narihito Okada, Kazuyuki Tadatomo, Yoichi Yamada
Summary: The study investigated the origin of multi-peak higher-energy emissions observed in InGaN/GaN quantum wells on MT-GaN layers, suggesting that the multi-peak emissions result from in-plane variations in In composition and/or well thickness. Experimental results indicate that diffusion of group III atoms between different facets in sub-micrometer scale V-pits might be responsible for the multiple higher-energy emissions observed in the InGaN/GaN quantum wells on MT-GaN.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Yuhao Ben, Feng Liang, Degang Zhao, Jing Yang, Ping Chen, Zongshun Liu
Summary: Direct evidence of the composition pulling effect (CPE) in InGaN quantum wells was obtained by combining energy dispersive x-ray spectrometry (EDS) and scanning tunneling electron microscope (STEM). The study found that the indium content increases along the c-axis in the InGaN quantum wells, forming an In-rich sublayer on the surface. The saturation of indium content in the In-rich sublayer leads to hindered incorporation of indium atoms, resulting in a decrease in the average indium composition in the quantum wells. Additionally, aggregation behavior of indium atoms was observed in samples with stronger CPE, leading to the formation of dark spot defects that significantly deteriorate the luminescence quality. By limiting the migration ability of indium atoms, dark spot defects can be greatly suppressed, leading to higher quality InGaN/GaN MQW with higher indium content.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Chemistry, Multidisciplinary
Mi-Hyang Sheen, Yong-Hee Lee, Jongjin Jang, Jongwoo Baek, Okhyun Nam, Cheol-Woong Yang, Young-Woon Kim
Summary: Surface undulation occurred during the growth of InGaN/GaN multi-quantum wells on a semi-polar m-plane (1-100) sapphire substrate. Two distinct facets were formed in the embedded MQWs, parallel to (11 (2) over bar2) and (01 (1) over bar 11), respectively. The structural and luminescence characteristics of these facets were investigated, and it was found that the indium incorporation differed between the two facets.
Article
Physics, Applied
Yao Chen, Camille Haller, Wei Liu, Sergey Yu Karpov, Jean-Francois Carlin, Nicolas Grandjean
Summary: This study investigates the impact of GaN-buffer growth temperature on the efficiency of InGaN/GaN quantum wells, revealing that high-temperature growth promotes the creation of surface defects leading to a collapse in internal quantum efficiency. Theoretical analysis suggests that these defects are likely to be nitrogen vacancies. Furthermore, the study shows that surface defects are mainly generated at the early stage of GaN growth and reach a steady state concentration determined by the growth temperature.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Yu Yin, Renfeng Chen, Yiwei Duo, Rui He, Jiankun Yang, Xiaoli Ji, Hao Long, Junxi Wang, Tongbo Wei
Summary: In this study, we investigated the carrier recombination and transportation process in dual-wavelength InGaN/GaN multiple quantum wells Micro-LED arrays under piezo-phototronic effects. The results showed that external strain influenced the violet electroluminescence (EL) intensity, but had little effect on the blue EL emission. Additionally, reducing the size of Micro-LED resulted in a decrease in the enhancement obtained via the piezo-phototronic effect. The study also found that strain-induced interface polarized charges increased the wave function overlap of electron-hole pairs but reduced the injection of hole carriers in the blue quantum well.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Applied
S. A. Church, M. Quinn, K. Cooley-Greene, B. Ding, A. Gundimeda, M. J. Kappers, M. Frentrup, D. J. Wallis, R. A. Oliver, D. J. Binks
Summary: Research indicates that growing InGaN/GaN quantum wells in the zincblende crystal phase has the potential to improve efficiency, with increasing the number and width of the quantum wells significantly enhancing emission efficiency.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Crystallography
Zhenyu Chen, Feng Liang, Degang Zhao, Jing Yang, Ping Chen, Desheng Jiang
Summary: The surface morphology and luminescence characteristics of InGaN/GaN multiple quantum wells were studied under different flow rates of ammonia during MOCVD growth to explore the optimal growth conditions for green laser diodes. Temperature-dependent photoluminescence (TDPL) examination revealed different emission peak characteristics, indicating significant structural changes in InGaN layers and the presence of composite structures of InGaN/GaN quantum wells and quantum-dot-like centers. It was found that these changes were caused by effects induced by ammonia, including promotion of indium incorporation, corrosion from hydrogen, and reduction in the surface energy of InGaN dot-like centers. Detailed research was conducted to determine ammonia's mechanism of action during InGaN layer growth.
Article
Physics, Applied
Johanna Meier, Patrick Haeuser, Christian Blumberg, Tim Smola, Werner Prost, Nils Weimann, Gerd Bacher
Summary: Site- and polarity-controlled core-shell InGaN/GaN nanorod LED structures were grown on Si(111) using metal organic vapor phase epitaxy. Uniform multiple quantum wells on polarization-free sidewalls were observed through scanning transmission electron microscope images. Spatially resolved photoluminescence mapping confirmed the emission at 3.0 eV from the polarization-free m-plane, with a fast recombination lifetime of about 490 ps at low temperatures. Quasi-resonant laser excitation demonstrated predominant radiative recombination at low excitation densities, while efficiency was decreased by Auger recombination and/or carrier leakage at high excitation densities.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Panpan Li, Haojun Zhang, Hongjian Li, Trevor Cohen, Ryan Anderson, Matthew S. Wong, Emily Trageser, Yi Chao Chow, Mattanjah de Vries, Shuji Nakamura, Steven P. DenBaars
Summary: We demonstrate room-temperature stimulated emission at 568 nm from low dislocation density InGaN/GaN multi-quantum wells. For a 1.4 mm long and a 50 mu m wide ridge bar optically pumped by a high-power pulsed laser, we observed an emission peak at 568 nm with a narrow spectral width of less than 2 nm at room temperature. The measured pumping threshold is less than 1.5 MW/cm(2), and the polarization ratio of the emission is over 90%. This demonstration paves the way for the future development of electrically injected InGaN semiconductor yellow laser diodes.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Physical
A. Y. Polyakov, L. A. Alexanyan, M. L. Skorikov, A. Chernykh, I. Shchemerov, V. N. Murashev, Tae-Hwan Kim, In-Hwan Lee, S. J. Pearton
Summary: The time-resolved photoluminescence (PL), current-voltage characteristics, and deep trap spectra of nanopillar GaN/InGaN multi-quantum-well (MQW) light-emitting diodes (LEDs) were studied after reactive ion etching (RIE) with different surface treatments. Treatments such as KOH etching and (NH4)(2)S sulfur passivation were effective in increasing the MQW PL band intensity and decreasing defect-related PL band intensity, but not in reducing RIE-induced excessive leakage current. Only annealing at >= 700 degrees C was able to strongly suppress the excessive leakage of the LEDs.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Crystallography
Sarai Zarate-Galvez, Abel Garcia-Barrientos, Roberto Ambrosio-Lazaro, Mario Garcia-Ramirez, Enrique Stevens-Navarro, Jairo Plaza-Castillo, Jose Hoyo-Montano, Obed Perez-Cortes
Summary: Simulations using the Nextnano++ software were conducted to investigate the influence of mobility on optoelectronic parameters in an InGaN/GaN blue LED. The results showed that lower mobility values resulted in lower leakage currents and stable photon emission. Doping-concentration mobility led to smaller wavelength shifts and narrower FWHM, making the photon emission more stable.
Article
Nanoscience & Nanotechnology
Jun Zhu, Bishi Ying
Summary: In this paper, a double-layer SiO2 photonic crystal LED with a linear defect structure in the p-GaN layer is proposed to improve the light extraction efficiency. By optimizing the structural parameters of the photonic crystal, the light extraction efficiency and light output power are significantly increased, while the I-V characteristics of the LED are unaffected.