Comparison between the Photoluminescence Mappings Under Selective and Non-selective Excitation and the Electroluminescence Mappings of the Epitaxial Wafers with InGaN-LED Structure

2006 ◽  
Vol 955 ◽  
Author(s):  
Kazuyuki Tadatomo ◽  
Osamu Shimoike ◽  
Hiromichi Noda ◽  
Masahiro Hiraoka ◽  
Kazumasa Yoshimura ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Selective Excitation ◽  
Excitation Power ◽  
Excitation Power Density ◽  
Peak Wavelength ◽  
Light Emitting ◽  
Forward Current ◽  
Pl Mapping ◽  
P Type

ABSTRACTWe compared the photoluminescence (PL) mappings of epitaxial wafers for light emitting diodes (LEDs) by using a He-Cd laser (325 nm line) and a laser diode (LD) with peak wavelength of 405 nm as excitation sources and the electroluminescence (EL) mappings of the same wafers. The samples were epitaxial wafers for blue and green InGaN-LEDs obtained in commercial. The wafers were fabricated into LEDs with a Ni/Au transparent p-type electrode and a Ti/Ni n-type electrode after the PL mapping measurements. The He-Cd laser performed the band to band excitation of (Al)GaN cladding and contact layers (non-selective excitation). Because the photo-excited carriers at the cladding and contact layers diffused into the multi-quantum wells (MQWs) and contributed the PL emission by radiative recombination in the MQWs, the PL mapping under the influence of the (Al)GaN cladding and contact layers was obtained. On the other hand, the LD (405 nm) enable us to obtain the PL mapping under selective excitation of the MQWs without the influence of the cladding and contact layers. The PL mapping measurements were carried out at room temperature (RT) at the excitation power density of 310 W/cm2 under non-selective excitation (by the He-Cd laser) and at that of 11.5 W/cm2 under selective excitation (by the LD). The EL mapping was measured at a forward current of 20 mA at RT. The area of the wafer with high EL intensity was coincident with the area with the high PL intensity under selective excitation. Therefore, the PL mapping measurement under selective excitation of MQWs is recommended to characterize the epitaxial wafers and to estimate the device performance of InGaN-LEDs.

UV Emission Mechanisms in Quaternary AlInGaN Epilayers and Multiple Quantum Wells

2002 ◽  
Vol 722 ◽  
Author(s):  
Mee-Yi Ryu ◽  
C. Q. Chen ◽  
E. Kuokstis ◽  
J. W. Yang ◽  
G. Simin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emitting Diode ◽  
Chemical Vapor ◽  
Excitation Power ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Excitation Power Density ◽  
Light Emitting ◽  
Uv Emission ◽  
Alloy Disorder

AbstractWe present the results on investigation and analysis of photoluminescence (PL) dynamics of quaternary AlInGaN epilayers and AlInGaN/AlInGaN multiple quantum wells (MQWs) grown by a novel pulsed metalorganic chemical vapor deposition (PMOCVD). The emission peaks in both AlInGaN epilayers and MQWs show a blueshift with increasing excitation power density. The PL emission of quaternary samples is attributed to recombination of carriers/excitons localized at band-tail states. The PL decay time increases with decreasing emission photon energy, which is a characteristic of localized carrier/exciton recombination due to alloy disorder. The obtained properties of AlInGaN materials grown by a PMOCVD are similar to those of InGaN. This indicates that the AlInGaN system is promising for ultraviolet applications such as the InGaN system for blue light emitting diode and laser diode applications.

Blue II-VI laser Diodes and light Emitting Diodes

1992 ◽  
Vol 281 ◽  
Author(s):  
R. L. Gunshor ◽  
A. V. Nurmikko ◽  
N. Otsuka
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Plasma Source ◽  
Threshold Current ◽  
Rf Plasma ◽  
Plan View ◽  
Light Emitting ◽  
Dislocation Densities ◽  
Power Outputs ◽  
P Type

ABSTRACTThe use of a nitrogen rf plasma source for p-type ZnSe grown by MBE, has allowed a variety of pn junction based devices to be realized. The pn junctions have been combined with (Zn,Cd)Se quantum wells to implement semiconductor injection lasers, operating in the blue/green portion of the spectrum, which were reported by 3M and the Brown/Purdue group in the summer of 1991. In the past year the field has moved rapidly. In particular, we can now report CW operation at low temperatures as well as pulsed operation at room temperature (490nm) using a Zn(S,Se)-based device configuration. Laser power output per facet for some designs is above 300 mW, and threshold current densities are as low as 1000A/cm 2 at room temperature. Lasing was demonstrated from devices grown on both p and n-type GaAs substrates. X-ray rocking curves of theII-VI regions exhibit FWHM values below 20 arcsec for specific samples. Dislocation densities are less than 105 cm−2, below the threshold of TEM plan view imaging. The blue LEDs provide power outputs in excess of 100μW while exhibiting external quantum efficiencies of 0.1% at room temperature.

Optical Study of Localized and Delocalized States in GaAsN/GaAs

2003 ◽  
Vol 798 ◽  
Author(s):  
Z. Y. Xu ◽  
X. D. Luo ◽  
X. D. Yang ◽  
P. H. Tan ◽  
C. L. Yang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Rapid Thermal Annealing ◽  
Short Pulse ◽  
Selective Excitation ◽  
Excitation Power ◽  
Pulse Excitation ◽  
Optical Study ◽  
Time Resolved ◽  
Exciton Localization ◽  
Time Resolved Photoluminescence

ABSTRACTTaking advantages of short pulse excitation and time-resolved photoluminescence (PL), we have studied the exciton localization effect in a number of GaAsN alloys and GaAsN/GaAs quantum wells (QWs). In the PL spectra, an extra transition located at the higher energy side of the commonly reported N-related emissions is observed. By measuring PL dependence on temperature and excitation power along with PL dynamics study, the new PL peak has been identified as a transition of the band edge-related recombination in dilute GaAsN alloy and delocalized transition in QWs. Using selective excitation PL we further attribute the localized emission in QWs to the excitons localized at the GaAsN/GaAs interfaces. This interface-related exciton localization could be greatly reduced by a rapid thermal annealing.

scholarly journals The Optical Properties of InGaN/GaN Nanorods Fabricated on (-201) β-Ga2O3 Substrate for Vertical Light Emitting Diodes

Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 42
Author(s):  
Jie Zhao ◽  
Weijiang Li ◽  
Lulu Wang ◽  
Xuecheng Wei ◽  
Junxi Wang ◽  
...  
Keyword(s):  
Stark Effect ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Strain Relaxation ◽  
Blue Shift ◽  
Peak Position ◽  
Excitation Power ◽  
Light Extraction Efficiency ◽  
Excitation Power Density ◽  
Light Emitting

We fabricated InGaN/GaN nanorod light emitting diode (LED) on (-201) β-Ga2O3 substrate via the SiO2 nanosphere lithography and dry-etching techniques. The InGaN/GaN nanorod LED grown on β-Ga2O3 can effectively suppress quantum confined Stark effect (QCSE) compared to planar LED on account of the strain relaxation. With the enhancement of excitation power density, the photoluminescence (PL) peak shows a large blue-shift for the planar LED, while for the nanorod LED, the peak position shift is small. Furthermore, the simulations also show that the light extraction efficiency (LEE) of the nanorod LED is approximately seven times as high as that of the planar LED. Obviously, the InGaN/GaN/β-Ga2O3 nanorod LED is conducive to improving the optical performance relative to planar LED, and the present work may lay the groundwork for future development of the GaN-based vertical light emitting diodes (VLEDs) on β-Ga2O3 substrate.

Effects of V/III ratio of InGaN quantum well at high growth temperature for near ultraviolet light emitting diodes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohd Ann Amirul Zulffiqal Md Sahar ◽  
Zainuriah Hassan ◽  
Sha Shiong Ng ◽  
Way Foong Lim ◽  
Khai Shenn Lau ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Quantum Wells ◽  
Ultraviolet Light ◽  
Light Output ◽  
Emission Peak ◽  
Organic Chemical ◽  
Peak Wavelength ◽  
Content Type ◽  
Light Emitting ◽  
Near Ultraviolet

Purpose The aims of this paper is to study the effects of the V/III ratio of indium gallium nitride (InGaN) quantum wells (QWs) on the structural, optical and electrical properties of near-ultraviolet light-emitting diode (NUV-LED). Design/methodology/approach InGaN-based NUV-LED is successfully grown on the c-plane patterned sapphire substrate at atmospheric pressure using metal organic chemical vapor deposition. Findings The indium composition and thickness of InGaN QWs increased as the V/III ratio increased from 20871 to 11824, according to high-resolution X-ray diffraction. The V/III ratio was also found to have an important effect on the surface morphology of the InGaN QWs and thus the surface morphology of the subsequent layers. Apart from that, the electroluminescence measurement revealed that the V/III ratio had a major impact on the light output power (LOP) and the emission peak wavelength of the NUV-LED. The LOP increased by up to 53% at 100 mA, and the emission peak wavelength of the NUV-LED changed to a longer wavelength as the V/III ratio decreased from 20871 to 11824. Originality/value This study discovered a relation between the V/III ratio and the properties of QWs, which resulted in the LOP enhancement of the NUV-LED. High TMIn flow rates, which produced a low V/III ratio, contribute to the increased LOP of NUV-LED.

The Properties of n-ZnO/p-SiC Heterojunctions and their Potential Applications for Devices

2006 ◽  
Vol 527-529 ◽  
pp. 1571-1574 ◽  
Author(s):  
Cole W. Litton ◽  
Ya.I. Alivov ◽  
D. Johnstone ◽  
Ümit Özgür ◽  
V. Avrutin ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Reverse Bias ◽  
Zno Films ◽  
Turn On ◽  
Forward Current ◽  
Current Voltage ◽  
Potential Applications ◽  
Current Voltage Characteristics ◽  
P Type

Heteroepitaxial n-ZnO films have been grown on commercial p-type 6H-SiC substrates by plasma-assisted molecular-beam epitaxy, and n-ZnO/p-SiC heterojunction mesa structures have been fabricated and their photoresponse properties have been studied. Current-voltage characteristics of the structures had a very good rectifying diode-like behavior with a leakage current less than 2 x 10-4 A/cm2 at -10 V, a breakdown voltage greater than 20 V, a forward turn on voltage of ∼5 V, and a forward current of ∼2 A/cm2 at 8 V. Photosensitivity of the diodes, when illuminated from ZnO side, was studied at room temperature and photoresponsivity of as high as 0.045 A/W at -7.5 V reverse bias was observed for photon energies higher than 3.0 eV.

Room temperature electroluminescence from arsenic doped p-type ZnO nanowires/n-ZnO thin film homojunction light-emitting diode

2014 ◽  
Vol 25 (4) ◽  
pp. 1955-1958 ◽  
Author(s):  
Hongwei Liang ◽  
Qiuju Feng ◽  
Xiaochuan Xia ◽  
Rong Li ◽  
Huiying Guo ◽  
...  
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Light Emitting Diode ◽  
Zno Nanowires ◽  
Zno Thin Film ◽  
Light Emitting ◽  
P Type

scholarly journals Nanoscale Characterization of Surface Plasmon-Coupled Photoluminescence Enhancement in Pseudo Micro Blue LEDs Using Near-Field Scanning Optical Microscopy

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 751
Author(s):  
Yufeng Li ◽  
Aixing Li ◽  
Ye Zhang ◽  
Peng Hu ◽  
Wei Du ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Optical Microscopy ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Near Field ◽  
Excitation Power ◽  
Localized Surface Plasmon ◽  
Excitation Density ◽  
Multiple Quantum ◽  
Excitation Power Density

The microcave array with extreme large aspect ratio was fabricated on the p-GaN capping layer followed by Ag nanoparticles preparation. The coupling distance between the dual-wavelength InGaN/GaN multiple quantum wells and the localized surface plasmon resonance was carefully characterized in nanometer scale by scanning near-field optical microscopy. The effects of coupling distance and excitation power on the enhancement of photoluminescence were investigated. The penetration depth was measured in the range of 39–55 nm depending on the excitation density. At low excitation power density, the maximum enhancement of 103 was achieved at the optimum coupling distance of 25 nm. Time-resolved photoluminescence shows that the recombination life time was shortened from 5.86 to 1.47 ns by the introduction of Ag nanoparticle plasmon resonance.

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