Influence of substrate orientation on photoluminescence in InGaN/GaN multiple quantum wells

2001 ◽  
Vol 693 ◽  
Author(s):  
P. Chen ◽  
S.J. Chua ◽  
W. Wang
Keyword(s):  
Quantum Wells ◽  
Quantum Wire ◽  
Peak Position ◽  
Excitation Power ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Excitation Power Density ◽  
Pl Spectra ◽  
Surface Steps ◽  
Peak Emission

AbstractIn this study, the photoluminescence (PL) spectra of InGaN/GaN multiple quantum wells (MQWs) grown on sapphire substrates with different orientation at 720°C were investigated at room temperature. Four different substrates were used, which have different surface step structures. Their orientations are: c-plane, a-plane, c-plane with off-set of 2 degree and c-plane with off-set of 6 degree towards a-plane. PL spectra from InGaN/GaN MQWs grown on c-plane substrates showed double-peak emission, while those from the MQWs grown on the others substrates showed single-peak emission. The strongest emission was found on the substrate with off-set of 2 degree towards a-plane. A Shift of PL peak position to long wavelength was observed on the substrates with an off-set angle. Meantime, all emissions were also investigated at different excitation power density. Experimental results indicate that the regular step structure on the substrates can seriously affect the growth of InGaN/GaN MQWs. Segregation effect in InGaN will lead to the high In composition regions (quantum-wire like structure) in the substrates with an off-set angle due to the regular steps on them, as observed by atomic force microscopy. It can be concluded that the surface steps on substrate play an important role in the formation of the In-rich InGaN quantum-wire like structure.

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.

Influence of in volatilization on photoluminescence in InGaN/GaN multiple quantum wells

2021 ◽  
Vol 11 (12) ◽  
pp. 2033-2038
Author(s):  
Kaiju Shi ◽  
Chengxin Wang ◽  
Rui Li ◽  
Shangda Qu ◽  
Zonghao Wu ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Internal Quantum Efficiency ◽  
Excitation Power ◽  
Localized States ◽  
Multiple Quantum ◽  
High Excitation ◽  
Rich Phase ◽  
Pl Spectra ◽  
Localization Effect ◽  
Effect Of Structure

Two multiple quantum well (MQW) InGaN/GaN structures emitting green light, without (A) and with (B) an indium (In) volatilization suppression technique (IVST) during growth of the active region, were fabricated. The dependencies of the photoluminescence (PL) spectra upon temperature at different levels of excitation power were investigated. The results indicate that an IVST can increase the In content while suppressing the phase separation caused by volatilization of that In incorporated in the well layers. Also, compared with Structure B with IVST, which contains one phase structure, Structure A without IVST, which contains two separate phases (i.e., an In-rich phase and an In-poor phase), exhibits higher internal quantum efficiency (IQE) at low excitation power and lower IQE at high excitation power. The former is mainly attributed to the stronger In-rich phase-related localization effect of Structure A, because the In-rich phase-related emission dominates the PL spectra of Structure A at a low excitation power; the latter is mainly due to the In-poor phase-related weaker localization effect of Structure A, because the In-poor phase-related emission dominates the PL spectra of Structure A at high excitation power because localized states in this In-rich phase are saturated.

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.

Lineshape Analysis of Intersubband Transitions in Multiple Quantum Wells

1995 ◽  
Vol 406 ◽  
Author(s):  
G. Gumbs
Keyword(s):  
Absorption Spectrum ◽  
Quantum Wells ◽  
Exchange Interaction ◽  
Phonon Scattering ◽  
Peak Position ◽  
Absorption Peak ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Intersubband Transitions ◽  
Electron Effective Mass

AbstractConduction intersubband transitions between the ground and first excited states in Al0.3Ga0.7As/GaAs multiple quantum wells (MQWs) are studied as a function of the twodimensional electron gas density (0.75 × 1012 ≤ σ ≤ 3.75 × 1012 cm−2) and temperature (5 ≤ T ≤ 300 K). There is no electron tunneling between the wells and well regions are uniformly doped with silicon donors. Theoretically, we have solved the Schrödinger equation containing the self-consistent Hartree potential, in which the z-dependencies of both electron effective mass and dielectric constant, as well as the non-parabolicity in the conduction energy subband dispersion have been taken into consideration. By applying many-body theory which includes the depolarization-shift from a collective dipole moment and the excitonicshift from the negative exchange interaction, we calculate the absorption spectrum as a function of the incident photon energy hw for different values of T and σ. From this, we can quantitatively analyze both T- and σ-dependencies of the peak position and the full width at half-maximum (FWHM) of peak values. The blue-shift or red-shift in the absorption peak position are quantitatively reproduced as either T or σ is reduced. The exchange interaction which depends on σ, will modify the energy subband dispersion. Therefore, the absorption peak will be broadened by the exchange interaction. The T-dependence of broadening from the optical-phonon scattering is also taken into account by a phenomenological model. From the calculated absorption spectrum as a function of o, we have successfully reproduced and explained the σ-dependence of FWHM measured in recent experiments.

Characteristics of polarization emission in a-plane GaN-based multiple quantum wells structures

2012 ◽  
Vol 1432 ◽  
Author(s):  
Chiao-Yun Chang ◽  
Huei-Min Huang ◽  
Tien-Chang Lu ◽  
Hao-Chung Kuo ◽  
Shing-Chung Wang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emission ◽  
Quantum Confinement Effect ◽  
Polarized Light ◽  
Peak Position ◽  
Multiple Quantum Wells ◽  
Experimental Result ◽  
Multiple Quantum ◽  
Polarization Ratio ◽  
Quantum Well Width

ABSTRACTWe studied the polarization-dependent photoluminescence (PL) of a-plane GaN /AlGaN multiple quantum wells (MQWs) grown on r-plane sapphire substrate with the various well width from 1.5 to 7.33 nm. To clarify the reasons of light emission polarization properties, we applied the 6×6 k‧p model to simulate the E-k dispersion relation and the wave functions to obtain the polarization optical transitions. According to the experimental result, the PL emission peak position exhibits a red-shifted with increasing well width, due to the reduction of the quantum confinement effect. The polarization ratio of a-plane GaN/AlGaN MQWs increased from 0.236 to 0.274 with increasing the quantum well width. This phenomenon is believed to be that y-polarized light emission gradually dominates the PL spectrum and thus enhances the polarization ratio.

scholarly journals Influence of excitation power and temperature on photoluminescence in InGaN/GaN multiple quantum wells

2012 ◽  
Vol 20 (4) ◽  
pp. 3932 ◽  
Author(s):  
Huining Wang ◽  
Ziwu Ji ◽  
Shuang Qu ◽  
Gang Wang ◽  
Yongzhi Jiang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Excitation Power ◽  
Multiple Quantum Wells ◽  
Multiple Quantum

Piezoelectric Effects in GaN/AlGaN Multiple Quantum Wells Probed by Picosecond Time-Resolved Photoluminescence

1998 ◽  
Vol 537 ◽  
Author(s):  
H. S. Kim ◽  
Y. Lin ◽  
H. X. Jiang ◽  
W. W. Chow ◽  
A. Botchkarev ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Peak Position ◽  
Multiple Quantum Wells ◽  
Collective Effects ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Delay Times ◽  
Piezoelectric Effects ◽  
Piezoelectric Field ◽  
Time Resolved Photoluminescence

AbstractPiezoelectric effects in GaN/AlGaN multiple quantum wells (MQWs) have been directly probed by picosecond time-resolved photoluminescence (PL) spectroscopy. The time-resolved PL spectra of the 40 Å well MQWs reveal that the PL transition peak position is in fact blueshifted at early delay times due to the collective effects of quantum confinement of carriers, piezoelectric field, and Coulomb screening. However, the spectral peak position shifts toward lower energies as the delay time increases and becomes redshifted at longer delay times. By comparing experimental and calculation results, we have obtained a low limit of the piezoelectric field strength to be about 560 kV/cm in the 40 Å well GaN/Al0.15Ga0.85N MQWs.

Photoluminescence Measurements in Interband Transition in Fast Neutron Irradiated In0.07Ga0.93As/A10.4Ga0.6 As Multiple Quantum Wells

1999 ◽  
Vol 607 ◽  
Author(s):  
M. O. Manasreh ◽  
S. Subramanian
Keyword(s):  
Quantum Wells ◽  
Fast Neutron ◽  
Irradiation Dose ◽  
Interband Transition ◽  
Peak Position ◽  
Multiple Quantum Wells ◽  
Fast Neutrons ◽  
Multiple Quantum ◽  
Interband Transitions ◽  
Many Body

AbstractInterband transitions in n-type InGaAs/AlGaAs multiple quantum wells were studied using a photoluminescence (PL) technique after the samples were irradiated with fast neutrons. It was observed that the PL intensity of the interband transition is reduced as the irradiation dose is increased. In Addition, the peak position energy of the interband transition was increased and then decreased as a function of irradiation dose. The results are explained in terms of electrons trapping, many-body effects, and irradiation-induced damages at the interfaces as well as in the well and barrier regions.

scholarly journals Piezoelectric Effects in GaN/AlGaN Multiple Quantum Wells Probed by Picosecond Time-Resolved Photoluminescence

1999 ◽  
Vol 4 (S1) ◽  
pp. 130-135
Author(s):  
H. S. Kim ◽  
J. Y. Lin ◽  
H. X. Jiang ◽  
W. W. Chow ◽  
A. Botchkarev ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Peak Position ◽  
Multiple Quantum Wells ◽  
Collective Effects ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Delay Times ◽  
Piezoelectric Effects ◽  
Piezoelectric Field ◽  
Time Resolved Photoluminescence

Piezoelectric effects in GaN/AlGaN multiple quantum wells (MQWs) have been directly probed by picosecond time-resolved photoluminescence (PL) spectroscopy. The time-resolved PL spectra of the 40 Å well MQWs reveal that the PL transition peak position is in fact blueshifted at early delay times due to the collective effects of quantum confinement of carriers, piezoelectric field, and Coulomb screening. However, the spectral peak position shifts toward lower energies as the delay time increases and becomes redshifted at longer delay times. By comparing experimental and calculation results, we have obtained a low limit of the piezoelectric field strength to be about 560 kV/cm in the 40 Å well GaN/Al0.15Ga0.85N MQWs.

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