Structural and Optical Studies of InGaN/GaN Superlattices Implanted with Eu Ions

MRS Advances ◽  
2017 ◽  
Vol 2 (3) ◽  
pp. 179-187
Author(s):  
Jingzhou Wang ◽  
Venkata R. Thota ◽  
Eric A. Stinaff ◽  
Mohammad Ebdah ◽  
Andre Anders ◽  
...  
Keyword(s):  
Stark Effect ◽  
Annealing Temperature ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Photoluminescence Spectra ◽  
Temperature Dependent ◽  
Optical Studies ◽  
Quantum Confined Stark Effect ◽  
Spectral Shifts ◽  
Before And After

ABSTRACTIn0.06Ga0.94N/GaN superlattices (SLs) grown on sapphire (0001) by metalorganic chemical vapor deposition were studied before and after europium (Eu) ion implantation to understand the strain induced-effects in the SL structure. The implanted SLs were investigated as a function of the thermal annealing temperature up to 1000 °C in nitrogen ambient. Temperature dependent photoluminescence spectra showed a red-shift of the SL emission peaks due the quantum confined Stark effect, followed by a blue-shift due to In atoms out-diffusion from the In0.06Ga0.94N quantum well, for both Eu ions implanted and unimplanted SLs. The amplitude of observed spectral shifts was smaller and the line width of the SLs emission peaks were narrower in the SLs:Eu3+ as compared to the unimplanted SLs. It is concluded that Eu3+ ions modified the strain in the SLs acting like impurity and/or defects getter in implantation degraded SLs resulting in material phase purification and improvements of SLs optical properties.

OPTICAL PROPERTIES OF GaInN/GaN MULTI-QUANTUM WELL STRUCTURE AND LIGHT EMITTING DIODE GROWN BY METALORGANIC CHEMICAL VAPOR PHASE EPITAXY

2007 ◽  
Vol 17 (01) ◽  
pp. 81-84
Author(s):  
J. Senawiratne ◽  
M. Zhu ◽  
W. Zhao ◽  
Y. Xia ◽  
Y. Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Well ◽  
Stark Effect ◽  
Light Emitting Diode ◽  
Chemical Vapor ◽  
Green Emission ◽  
Luminescence Spectroscopy ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Multi Quantum Well

Optical properties of green emission Ga 0.80 In 0.20 N/GaN multi-quantum well and light emitting diode have been investigated by using photoluminescence, cathodoluminescence, electroluminescence, and photoconductivity. The temperature dependent photoluminescence and cathodoluminescence studies show three emission bands including GaInN/GaN quantum well emission centered at 2.38 eV (~ 520 nm). The activation energy of the non-radiative recombination centers was found to be ~ 60 meV. The comparison of photoconductivity with luminescence spectroscopy revealed that optical properties of quantum well layers are strongly affected by the quantum-confined Stark effect.

Polarization effects in AlxGa1−xN / GaN superlattices

2000 ◽  
Vol 639 ◽  
Author(s):  
Erik L. Waldron ◽  
E. Fred Schubert ◽  
John W. Graff ◽  
Andrei Osinsky ◽  
Michael J. Murphy ◽  
...  
Keyword(s):  
Room Temperature ◽  
Stark Effect ◽  
Blue Shift ◽  
Transition Band ◽  
Polarization Effects ◽  
Quantum Confined Stark Effect ◽  
Free Carriers ◽  
Bulk Gan ◽  
Band Transition ◽  
Photoluminescence Studies

ABSTRACTRoom temperature and low temperature photoluminescence studies of AlxGa1−xN/GaN superlattices reveal a red shift of the dominant transition band relative to the bulk GaN bandgap. The shift is attributed to the quantum-confined Stark effect resulting from polarization fields in the superlattices. A theoretical model for the band-to-band transition energies based on perturbation theory and a variational approach is developed. Comparison of the experimental data with this model yields a polarization field of 4.6 × 105 V/cm for room temperature Al0.1Ga0.9N/GaN and 4.5 × 105 V/cm for room temperature Al0.2Ga0.8N/GaN. At low temperatures the model yields 5.3 × 105 V/cm for Al0.1Ga0.9N/GaN and 6.3 × 105 V/cm for Al0.2Ga0.8N/GaN. The emission bands exhibit a blue shift at high excitation densities indicating screening of internal polarization fields by photo-generated free carriers.

Preparation and Spectrial Studies of Silicon Nitride Thin Films Containing Amorphous Silicon Quantum Dots

2021 ◽  
Vol 323 ◽  
pp. 48-55
Author(s):  
Jia Xin Sun ◽  
Bing Qing Zhou ◽  
Xin Gu
Keyword(s):  
Thin Films ◽  
Quantum Dots ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Raman Spectra ◽  
Annealing Temperature ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Silicon Quantum Dots ◽  
Plasma Chemical Vapor Deposition

Silicon-rich silicon nitride thin films are prepared on P-type monocrystalline silicon wafer (100) and glass substrate by plasma chemical vapor deposition with reaction gas sources SiH4 and NH3. The deposited samples are thermally annealed from 600°C to 1000°C in an atmosphere furnace filled with high purity nitrogen. The annealing time is 60 minutes. Fourier transform infrared spectroscopy (FTIR) is carried out to investigate the bonding configurations in the films. The results show that the Si-H bond and N-H bond decrease with the increase of annealing temperature, and completely disappear at the annealing temperature of 900°C. But the Si-N bond is enhanced with the increase of annealing temperature, and the blue shift occurs, then Si content in the film increases. The Raman Spectra show that the amorphous Si Raman peak appears at 480 cm-1 in the film at 700°C. The Raman spectra of the films annealed at 1000 °C is fitted with two peaks, and a peak at 497 cm -1 is found, which indicated that the Si phase in the films changed from amorphous to crystalline with the increase of annealing temperature. The experiment also analyses the luminescence properties of the samples through PL spectrum, and it is found that there are five luminescence peaks in each sample under different annealing temperature. Based on the analysis of Raman spectrum and FTIR spectrum, the PL peak of amorphous silicon quantum dots appears at the wavelength range of 525-555nm, and the other four PL peaks are all from the defect state luminescence in the thin films, and the amorphous silicon quantum dot size is calculated according to the formula.

scholarly journals AlGaN Nanowires for Ultraviolet Light-Emitting: Recent Progress, Challenges, and Prospects

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 125 ◽  
Author(s):  
Songrui Zhao ◽  
Jiaying Lu ◽  
Xu Hai ◽  
Xue Yin
Keyword(s):  
Aluminum Gallium Nitride ◽  
Recent Progress ◽  
Stark Effect ◽  
Uv Light ◽  
Chemical Vapor ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Recent Developments ◽  
Uv Leds ◽  
Made In

In this paper, we discuss the recent progress made in aluminum gallium nitride (AlGaN) nanowire ultraviolet (UV) light-emitting diodes (LEDs). The AlGaN nanowires used for such LED devices are mainly grown by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD); and various foreign substrates/templates have been investigated. Devices on Si so far exhibit the best performance, whereas devices on metal and graphene have also been investigated to mitigate various limitations of Si substrate, e.g., the UV light absorption. Moreover, patterned growth techniques have also been developed to grow AlGaN nanowire UV LED structures, in order to address issues with the spontaneously formed nanowires. Furthermore, to reduce the quantum confined Stark effect (QCSE), nonpolar AlGaN nanowire UV LEDs exploiting the nonpolar nanowire sidewalls have been demonstrated. With these recent developments, the prospects, together with the general challenges of AlGaN nanowire UV LEDs, are discussed in the end.

Photoluminescence and Recombination Mechanisms in Nitride-Based Multiple Quantum Wells

2015 ◽  
Vol 764-765 ◽  
pp. 1250-1254
Author(s):  
Ya Fen Wu ◽  
Jiunn Chyi Lee
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Multiple Quantum Well ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Multiple Quantum ◽  
Incident Power ◽  
Quantum Confined Stark Effect ◽  
Metal Organic ◽  
Quantum Confined

The InGaN/AlGaN multiple-quantum-well heterostructures were fabricated by metal-organic chemical vapor deposition system with different indium and aluminum content during the growth of InGaN well layers and AlGaN barrier layers. Temperature-and incident-power-dependent photoluminescence were carried out to examine the recombination mechanisms in the heterostructures. Both of the localization effect and quantum-confined Stark effect are considered. From the experimental and theoretical analysis, the dependence of optical characteristics on the temperature and incident-power are consistent with the recombination mechanisms involving band-tail states and the screen of quantum-confined Stark effect.

The Investigation of InGaN MQW Electroabsorption Modulator using the LED/Modulator/Detector Monolithically Integrated Structure

2000 ◽  
Vol 639 ◽  
Author(s):  
S.W. Chung ◽  
Y.S. Zhao ◽  
C.H. Lin ◽  
H.P. Lee
Keyword(s):  
Stark Effect ◽  
Piezoelectric Effect ◽  
Free Exciton ◽  
Stokes Shift ◽  
Blue Shift ◽  
Electroabsorption Modulator ◽  
Quantum Well Structures ◽  
Quantum Confined Stark Effect ◽  
Monolithically Integrated ◽  
Emission And Absorption Spectra

ABSTRACTThe strong piezoelectric effect and quantum confined stark effect (QCSE) in the InGaN/GaN quantum well structures allow one to modify the free exciton absorption by the extrinsic field. The QCSE is investigated using a monolithically integrated three-section device comprising an LED, electroabsorption modulator and a detector section. The experimental results show that the LED output can be modulated as indicated by the detector signal. The strength of modulation decreases monotonically with increasing In composition in the InGaN/GaN MQW. The result can be explained on the basis of the Stokes' shift between the emission and absorption spectra in the InGaN/GaN QW structure, and a blue shift of the absorption spectrum due to the QCSE as a result of the piezoelectric effect.

PROPOSAL OF NOVEL STRUCTURE LIGHT EMITTING DEVICES CONSISTING OF InN/GaN MQWs WITH ULTRATHIN InN WELLS IN GaN MATRIX

2008 ◽  
Vol 18 (04) ◽  
pp. 993-1003 ◽  
Author(s):  
AKIHIKO YOSHIKAWA ◽  
SONG-BEK CHE
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Blue Shift ◽  
Growth Conditions ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Quantum Confined Stark Effect ◽  
Novel Structure ◽  
Structure Light

Novel structure light emitting diodes (LEDs) made of InN / GaN multiple quantum wells (MQWs) are proposed and demonstrated. The MQWs consisted of very fine and narrow 1 monolayer (ML)-thick InN wells embedded in GaN matrix, which were successfully fabricated by radio-frequency molecular beam epitaxy. The thickness of InN wells can be fractional ML and/or two MLs depending on the growth conditions, resulting in different wavelength light emissions from deep violet to blue. Epitaxy processes for the MQWs fabrication are very unique on the basis of the self-ordering and coherent growth mode for atomically flat ~1 ML InN well deposition on GaN template. It is shown that the epitaxy temperature for 1 ML InN wells can be much higher than the highest epitaxy temperature of thick InN layer due to the effects of GaN matrix. Bright electroluminescence (EL) emission is observed at 418 nm at room temperature in LEDs fabricated by the MQWs. Further it is confirmed that the quantum confined Stark effect (QCSE) in InN wells is remarkably reduced due to the effects with using ultimately thin InN wells as active layers, resulting an extremely small blue shift in the EL peak wavelengths for two orders different injection current levels.

Recombination Dynamics of InGaN/GaN Multiple Quantum Wells With Different Well Thickness

MRS Advances ◽  
2016 ◽  
Vol 1 (2) ◽  
pp. 197-202 ◽  
Author(s):  
X. C. Wei ◽  
L. Zhang ◽  
N. Zhang ◽  
J. X. Wang ◽  
J. M. Li
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Stark Effect ◽  
Turning Point ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Temperature Dependent ◽  
Quantum Confined Stark Effect ◽  
Exciton Localization ◽  
Recombination Dynamics

ABSTRACTRecombination dynamics of InGaN/GaN multiple quantum wells (MQWs) with different well thickness have been studied. From the behaviour of temperature dependent photoluminescence, we find that the activation energy decreases with the well thickness increasing. In addition, with temperature changing from 10K to room temperature, the “W” shape of full width of half maximum is also thickness related, and it becomes more obvious with the well thickness increasing. These results indicate that the dominant recombination dynamics change from exciton localization to quantum confined stark effect with well thickness increasing. From our measurement, the InGaN/GaN MQWs with 3nm thickness seems a turning point, which shows the best optimized optical and structural properties.

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