Short-period AlGaN based superlattices for deep UV light emitting diodes grown by gas source molecular beam epitaxy

2005 ◽  
Vol 892 ◽  
Author(s):  
Sergey Nikishin ◽  
Boris Borisov ◽  
Vladimir Kuryatkov ◽  
Mark Holtz ◽  
Henryk Temkin
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Light Emission ◽  
Uv Light ◽  
Growth Mode ◽  
Light Emitting ◽  
Gas Source ◽  
Luminescence Efficiency ◽  
Short Period ◽  
Short Period Superlattices

AbstractWe report the results of two studies of the growth and physical properties of AlGaN-based short-period superlattices (SPSLs), each aimed at improving light emission. In the first experiment, we grow structures on bulk AlN substrates. We observe ∼ 3 times higher luminescence efficiency than identically grown structures on sapphire. In the second experiment, we grow structures on sapphire while controlling the growth mode. We observe a significant improvement in the room temperature cathodoluminescence efficiency (at least by factor of 10) of AlGaN quantum wells when the 3D growth mode is induced by reduced flux of ammonia over identically prepared structures grown in the 2D mode.

n-Type Diamond Growth by Phosphorus Doping

2007 ◽  
Vol 1039 ◽  
Author(s):  
Hiromitsu Kato ◽  
Toshiharu Makino ◽  
Satoshi Yamasaki ◽  
Hideyo Okushi
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Light Emission ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Diamond Growth ◽  
Phosphorus Doping ◽  
Light Emitting ◽  
Compensation Ratio ◽  
Phosphorus Doped

AbstractPhosphorus doping on (001)-oriented diamond is introduced and compared with results achieved on (111) diamond. Detailed procedures, conditions, doping characteristics, and recent electrical properties of (001) phosphorus-doped diamond films are described. Now the highest mobility is reached to be ∼780 cm2/Vs at room temperature. The carrier compensation ratio, which is still high around 50-80 %, is the most important issues for (001) phosphorus-doped diamond to improve its electrical property. The origin of compensators in phosphorus-doped diamond is investigated, while yet to be identified.Ultraviolet light emitting diode with p-i-n junction structure is also introduced using (001) n-type diamond. A strong UV light emission at around ∼240 nm is observed even at room temperature. High performance of diamond UV-LED is demonstrated.

scholarly journals III-Nitride Short Period Superlattices for Deep UV Light Emitters

2018 ◽  
Vol 8 (12) ◽  
pp. 2362 ◽  
Author(s):  
Sergey Nikishin
Keyword(s):  
Uv Light ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Light Emitters ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Short Period ◽  
Short Period Superlattices ◽  
Metal Organic ◽  
Deep Uv

III-Nitride short period superlattices (SPSLs), whose period does not exceed ~2 nm (~8 monolayers), have a few unique properties allowing engineering of light-emitting devices emitting in deep UV range of wavelengths with significant reduction of dislocation density in the active layer. Such SPSLs can be grown using both molecular beam epitaxy and metal organic chemical vapor deposition approaches. Of the two growth methods, the former is discussed in more detail in this review. The electrical and optical properties of such SPSLs, as well as the design and fabrication of deep UV light-emitting devices based on these materials, are described and discussed.

Optical Properties of AlN/AlGa(In)N Short Period Superlattices – Deep UV Light Emitting Diodes

2003 ◽  
Vol 798 ◽  
Author(s):  
M. Holtz ◽  
I. Ahmad ◽  
V. V. Kuryatkov ◽  
B. A. Borisov ◽  
G. D. Kipshidze ◽  
...  
Keyword(s):  
Optical Properties ◽  
Buffer Layer ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Effusion Cell ◽  
Light Emitting ◽  
Short Period ◽  
Short Period Superlattices ◽  
Deep Uv ◽  
P Type

ABSTRACTWe report optical properties of deep UV light emitting diodes (LEDs). Devices are based on short period superlattices of AlN/AlxGa1-x(In)N (x ∼ 0.08) grown by gas source molecular beam epitaxy with ammonia. Structures consist of a 50-nm thick AlN nucleation/buffer layer deposited on sapphire. This is followed by a 1-micron thick Si-doped buffer layer of AlGaN or AlN/AlGa(In)N designed to be transparent for wavelengths longer than 240 nm. The design thickness of the superlattice well layers is systematically varied from 0.50 nm to 1.25 nm and the thickness of the barrier is varied from 0.75 nm to 2.00 nm. The n- and p-type SPSLs were doped with Si derived from silane and Mg evaporated from an effusion cell, respectively. We investigate device structures as well as superlattices which are nominally undoped, p-type, and n-type. Optical properties are investigated using reflectance, cathodoluminescence, and, in the case of LEDs, using electroluminescence. By controlling the properties of the superlattice, we obtain optical gaps ranging from 4.5 eV (276 nm) and 5.3 eV (234 nm). A systematic shift between the optical gap and the CL peak emission energy is discussed. Electrical properties are studied using I-V, C-V, and Hall effect. LEDs based on these superlattices and operating in the range of 260 to 280 nm exhibit turn-on voltages in the range of 4 to 6 V and support dc current densities in excess of 500 A/cm2 at room temperature. We present results on the electrical and optical properties of our LEDs designed using these studies.

InAs Quantum Dots in AlAs/GaAs Short Period Superlattices: Structure, Optical Characteristics and Laser Diodes

2001 ◽  
Vol 707 ◽  
Author(s):  
Vadim Tokranov ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
K. Dovidenko ◽  
R. Todt ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Inas Quantum Dots ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices ◽  
Emitting Lasers ◽  
Cladding Layers

ABSTRACTThe influence of two monolayer - thick AlAs under- and overlayers on the formation and properties of self-assembled InAs quantum dots (QDs) has been studied using transmission electron microscopy (TEM) and photoluminescence (PL). Single sheets of InAs QDs were grown inside a 2ML/8ML AlAs/GaAs short-period superlattice with various combinations of under- and overlayers. It was found that 2.4ML InAs QDs with GaAs underlayer and 2ML AlAs overlayer exhibited the lowest QD surface density of 4.2x1010 cm-2 and the largest QD lateral size of about 19 nm as compared to the other combinations of cladding layers. This InAs QD ensemble has also shown the highest room temperature PL intensity with a peak at 1210 nm and the narrowest linewidth, 34 meV. Fabricated edge-emitting lasers using triple layers of InAs QDs with AlAs overlayer demonstrated 120 A/cm2 threshold current density and 1230 nm emission wavelength at room temperature. Excited state QD lasers have shown high thermal stability of threshold current up to 130°C.

Growth and properties of near-UV light emitting diodes based on InN/GaN quantum wells

2008 ◽  
Vol 205 (5) ◽  
pp. 1070-1073 ◽  
Author(s):  
E. Dimakis ◽  
A. Yu. Nikiforov ◽  
C. Thomidis ◽  
L. Zhou ◽  
D. J. Smith ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Light Emitting

Light Emission from Intrinsic and Doped Silicon-Rich Silicon Oxide: from the Visible to 1.6 ΜM

1996 ◽  
Vol 452 ◽  
Author(s):  
L. Tsybeskov ◽  
K. L. Moore ◽  
P. M. Fauchet ◽  
D. G. Hall
Keyword(s):  
Rare Earth ◽  
External Quantum Efficiency ◽  
Room Temperature ◽  
Structural Modification ◽  
Silicon Oxide ◽  
Light Emission ◽  
Crystalline Silicon ◽  
Light Emitting ◽  
Infra Red ◽  
Doped Silicon

AbstractSilicon-rich silicon oxide (SRSO) films were prepared by thermal oxidation (700°C-950°C) of electrochemically etched crystalline silicon (c-Si). The annealing-oxidation conditions are responsible for the chemical and structural modification of SRSO as well as for the intrinsic light-emission in the visible and near infra-red spectral regions (2.0–1.8 eV, 1.6 eV and 1.1 eV). The extrinsic photoluminescence (PL) is produced by doping (via electroplating or ion implantation) with rare-earth (R-E) ions (Nd at 1.06 μm, Er at 1.5 μm) and chalcogens (S at ∼1.6 μm). The impurities can be localized within the Si grains (S), in the SiO matrix (Nd, Er) or at the Si-SiO interface (Er). The Er-related PL in SRSO was studied in detail: the maximum PL external quantum efficiency (EQE) of 0.01–0.1% was found in samples annealed at 900°C in diluted oxygen (∼ 10% in N2). The integrated PL temperature dependence is weak from 12K to 300K. Light emitting diodes (LEDs) with an active layer made of an intrinsic and doped SRSO are manufactured and studied: room temperature electroluminescence (EL) from the visible to 1.6 μmhas been demonstrated.

High-efficiency near-UV light-emitting diodes on Si substrates with InGaN/GaN/AlGaN/GaN multiple quantum wells

2020 ◽  
Vol 8 (3) ◽  
pp. 883-888 ◽  
Author(s):  
Yuan Li ◽  
Zhiheng Xing ◽  
Yulin Zheng ◽  
Xin Tang ◽  
Wentong Xie ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Multiple Quantum ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Si Substrates

High quantum efficiency LEDs with InGaN/GaN/AlGaN/GaN MQWs have been demonstrated. The proposed GaN interlayer barrier can not only increase the concentration and the spatial overlap of carriers, but also improve the quality of the MQWs.

Light Emitting Diode with MOS Structures Containing Multiple-Stacked Si Quantum Dots

2007 ◽  
Vol 121-123 ◽  
pp. 557-560 ◽  
Author(s):  
J. Xu ◽  
Katsunori Makihara ◽  
Hidenori Deki ◽  
Yoshihiro Kawaguchi ◽  
Hideki Murakami ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Luminescence Intensity ◽  
Room Temperature ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Infrared Light ◽  
Gate Bias ◽  
Light Emitting ◽  
Mos Structures ◽  
Si Quantum Dots

Light emitting diode with MOS structures containing multiple-stacked Si quantum dots (QDs)/SiO2 was fabricated and the visible-infrared light emission was observed a room temperature when the negative gate bias exceeded the threshold voltage. The luminescence intensity was increased linearly with increasing the injected current density. The possible luminescence mechanism was briefly discussed and the delta P doping was performed to obtain the doped Si QDs and the improvement of EL intensity was demonstrated.

scholarly journals The Structural, Electronic, and Optical Properties of Ge/Si Quantum Wells: Lasing at a Wavelength of 1550 nm

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 1006
Author(s):  
Hongqiang Li ◽  
Jianing Wang ◽  
Jinjun Bai ◽  
Shanshan Zhang ◽  
Sai Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Room Temperature ◽  
Light Emission ◽  
Single Mode ◽  
Group Iv ◽  
Light Power ◽  
Fully Integrated ◽  
Electronic And Optical Properties ◽  
Novel Approach

The realization of a fully integrated group IV electrically driven laser at room temperature is an essential issue to be solved. We introduced a novel group IV side-emitting laser at a wavelength of 1550 nm based on a 3-layer Ge/Si quantum well (QW). By designing this scheme, we showed that the structural, electronic, and optical properties are excited for lasing at 1550 nm. The preliminary results show that the device can produce a good light spot shape convenient for direct coupling with the waveguide and single-mode light emission. The laser luminous power can reach up to 2.32 mW at a wavelength of 1550 nm with a 300-mA current. Moreover, at room temperature (300 K), the laser can maintain maximum light power and an ideal wavelength (1550 nm). Thus, this study provides a novel approach to reliable, efficient electrically pumped silicon-based lasers.

An Ultra-Simple Method for Synthesis of Violet CdS Quantum Dots at Sub-Room Temperature

2020 ◽  
Vol 20 (6) ◽  
pp. 3935-3938 ◽  
Author(s):  
Chandan Yadav ◽  
Karan Surana ◽  
Pramod K. Singh ◽  
Bhaskar Bhattacharya
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Uv Light ◽  
Xrd Analysis ◽  
Wet Chemical Method ◽  
Simple Method ◽  
Light Emitting ◽  
Violet Color ◽  
Wet Chemical ◽  
Sensitized Solar Cells

The emergence of fluorescence quantum dots (QDs) has led to the development of variety of applications in science and technology. Owing to the diverse optical and electrical properties of CdS QDs we have synthesized the same using wet chemical method. The QDs have been prepared at sub-room temperature using a new solvent comprising a mixture of water and methanol. The QDs when seen under UV light radiate violet color. The band-gap of the QDs deduced from the absorption spectra was 3.08 eV while PL spectra of the QDs suggested possibility of multiple exciton generation with a close to narrow size distribution. XRD analysis confirmed cubic structure of the particles. The obtained results suggest that these QDs can play ideal role in quantum dot sensitized solar cells (QDSSC) or in light emitting diodes (LEDs).

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