Multiwafer Movpe of III-Nitride Films for Led and Laser Applications

1997 ◽  
Vol 482 ◽  
Author(s):  
R. Beccard ◽  
O. Schoen ◽  
B. Schineller ◽  
D. Schmitz ◽  
M. Heuken ◽  
...  
Keyword(s):  
Room Temperature ◽  
State Of The Art ◽  
Low Cost ◽  
Free Exciton ◽  
Single Layer ◽  
Laser Applications ◽  
Room Temperature Photoluminescence ◽  
Cost Of Ownership ◽  
P Type ◽  
Better Than

AbstractProcess for mass production of GaN and its related alloys, InGaN and AlGaN, have been optimized to achieve high device yield and low cost of ownership. Here we present some of the latest results obtained from AIX 2000 HT Planetary Reactor® in a configuration of 7×2” which provides unique uniformity capabilities due to the two fold rotation of the substrates. GaiN single layers with background electron concentrations below 5·1016 cm-3 and intended doping levels up to 1018 cm-3 p-type and 1020 cm-3 n-type with state of the art homogeneities have been achieved. Thickness homogeneities have been shown to be better than 1% standard deviation on full 2” wafers, while composition uniformity of ternary material is determined by room temperature photoluminescence mappings. Low temperature photoluminescence and reflectance spectra of single layer GaN revealed free exciton transitions.

A Novel Wideband transition from Substrate Integrated Waveguide to Rectangular Waveguide

2020 ◽  
Vol 10 ◽  
Author(s):  
Keyur Mahant ◽  
Hiren Mewada ◽  
Amit Patel ◽  
Alpesh Vala ◽  
Jitendra Chaudhari
Keyword(s):  
Rectangular Waveguide ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Single Layer ◽  
Circuit Board ◽  
Substrate Integrated Waveguide ◽  
Ka Band ◽  
Better Than ◽  
Millimeter Wave Circuits ◽  
Wideband Transition

Aim: In this article, wideband substrate integrated waveguide (SIW) and rectangular waveguide (RWG) transition operating in Ka-band is proposed Objective: In this article, wideband substrate integrated waveguide (SIW) and rectangular waveguide (RWG) transition operating in Ka-band is proposed. Method: Coupling patch etched on the SIW cavity to couple the electromagnetic energy from SIW to RWG. Moreover, metasurface is introduced into the radiating patch to enhance bandwidth. To verify the functionality of the proposed structure back to back transition is designed and fabricated on a single layer substrate using standard printed circuit board (PCB) fabrication technology. Results: Measured results matches with the simulation results, measured insertion loss is less than 1.2 dB and return loss is better than 3 dB for the frequency range of 28.8 to 36.3 GHz. By fabricating transition with 35 SRRs bandwidth of the proposed transition can be improved. Conclusion: The proposed transition has advantages like compact in size, easy to fabricate, low cost and wide bandwidth. Proposed structure is a good candidate for millimeter wave circuits and systems.

scholarly journals Single-Layer Line-Fed Broadband Microstrip Patch Antenna on Thin Substrates

Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 37
Author(s):  
Roberto Vincenti Gatti ◽  
Riccardo Rossi ◽  
Marco Dionigi
Keyword(s):  
Patch Antenna ◽  
State Of The Art ◽  
Low Cost ◽  
Single Layer ◽  
Microstrip Antennas ◽  
Microstrip Patch Antenna ◽  
Layer Line ◽  
Limited Bandwidth ◽  
Microstrip Patch ◽  
Effective Design

In this work, the issue of limited bandwidth typical of microstrip antennas realized on a single thin substrate is addressed. A simple yet effective design approach is proposed based on the combination of traditional single-resonance patch geometries. Two novel shaped microstrip patch antenna elements with an inset feed are presented. Despite being printed on a single-layer substrate with reduced thickness, both radiators are characterized by a broadband behavior. The antennas are prototyped with a low-cost and fast manufacturing process, and measured results validate the simulations. State-of-the-art performance is obtained when compared to the existing literature, with measured fractional bandwidths of 3.71% and 6.12% around 10 GHz on a 0.508-mm-thick Teflon-based substrate. The small feeding line width could be an appealing feature whenever such radiating elements are to be used in array configurations.

Room Temperature Band-Edge Luminescence from Silicon Grains Prepared by the Recrystallization of Mesoporous Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
Karen L. Moore ◽  
Leonid Tsybeskov ◽  
Philippe M. Fauchet ◽  
Dennis G. Hall
Keyword(s):  
Room Temperature ◽  
Silicon Oxide ◽  
Crystalline Silicon ◽  
Band Edge ◽  
Applied Bias ◽  
Mesoporous Silicon ◽  
Room Temperature Photoluminescence ◽  
Band Edge Luminescence ◽  
A Current ◽  
Better Than

AbstractRoom-temperature photoluminescence (PL) peaking at 1.1 eV has been found in electrochemically etched mesoporous silicon annealed at 950°C. Low-temperature PL spectra clearly show a fine structure related to phonon-assisted transitions in pure crystalline silicon (c-Si) and the absence of defect-related (e.g.P-line) and impurity-related (e.g.oxygen, boron) transitions. The maximum PL external quantum efficiency (EQE) is found to be better than 0.1% with a weak temperature dependence in the region from 12K to 400K. The PL intensity is a linear function of excitation intensity up to 100 W/cm2. The PL can be suppressed by an external electric field ≥ 105 V/cm. Room temperature electroluminescence (EL) related to the c-Si band-edge is also demonstrated under an applied bias ≤ 1.2 V and with a current density ≈ 20 mA/cm2. A model is proposed in which the radiative recombination originates from recrystallized Si grains within a non-stoichiometric Si-rich silicon oxide (SRSO) matrix.

GalnAsSb Materials for Thermophotovoltaics

1996 ◽  
Vol 450 ◽  
Author(s):  
C. A. Wang ◽  
G. W. Turner ◽  
M. J. Manfra ◽  
H. K. Choi ◽  
D. L. Spears
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Hole Concentration ◽  
Organometallic Vapor Phase Epitaxy ◽  
Room Temperature Photoluminescence ◽  
P Type ◽  
First Time ◽  
Lattice Matched ◽  
Comparable Quality ◽  
Peak Emission

ABSTRACTGai1−xInxASySb1-y (0.06 < x < 0.18, 0.05 < y < 0.14) epilayers were grown lattice-matched to GaSb substrates by low-pressure organometallic vapor phase epitaxy (OMVPE) using triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony. These epilayers have a mirror-like surface morphology, and exhibit room temperature photoluminescence (PL) with peak emission wavelengths (λP,300K) out to 2.4 μm. 4K PL spectra have a full width at half-maximum of 11 meV or less for λP,4K < 2.1 μm (λP,300K = 2.3 μm). Nominally undoped layers are p-type with typical 300K hole concentration of 9 × 1015 cm−3 and mobility ∼ 450 to 580 cm2/V-s for layers grown at 575°C. Doping studies are reported for the first time for GalnAsSb layers doped n type with diethyltellurium and p type with dimethylzinc. Test diodes of p-GalnAsSb/n-GaSb have an ideality factor that ranges from 1.1 to 1.3. A comparison of electrical, optical, and structural properties of epilayers grown by molecular beam epitaxy indicates OMVPE-grown layers are of comparable quality.

scholarly journals Reversible Room Temperature H2 Gas Sensing Based on Self-Assembled Cobalt Oxysulfide

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 303
Author(s):  
Hui Zhou ◽  
Kai Xu ◽  
Nam Ha ◽  
Yinfen Cheng ◽  
Rui Ou ◽  
...  
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Gas Sensing ◽  
Low Cost ◽  
High Sensitivity ◽  
Cobalt Sulfide ◽  
Bandgap Energy ◽  
Gas Molecules ◽  
Self Assembled ◽  
P Type

Reversible H2 gas sensing at room temperature has been highly desirable given the booming of the Internet of Things (IoT), zero-emission vehicles, and fuel cell technologies. Conventional metal oxide-based semiconducting gas sensors have been considered as suitable candidates given their low-cost, high sensitivity, and long stability. However, the dominant sensing mechanism is based on the chemisorption of gas molecules which requires elevated temperatures to activate the catalytic reaction of target gas molecules with chemisorbed O, leaving the drawbacks of high-power consumption and poor selectivity. In this work, we introduce an alternative candidate of cobalt oxysulfide derived from the calcination of self-assembled cobalt sulfide micro-cages. It is found that the majority of S atoms are replaced by O in cobalt oxysulfide, transforming the crystal structure to tetragonal coordination and slightly expanding the optical bandgap energy. The H2 gas sensing performances of cobalt oxysulfide are fully reversible at room temperature, demonstrating peculiar p-type gas responses with a magnitude of 15% for 1% H2 and a high degree of selectivity over CH4, NO2, and CO2. Such excellent performances are possibly ascribed to the physisorption dominating the gas–matter interaction. This work demonstrates the great potentials of transition metal oxysulfide compounds for room-temperature fully reversible gas sensing.

Properties of Different Room-Temperature Photoluminescence Bands in 4H-SiC Substrates Investigated by Mapping Techniques

2007 ◽  
Vol 556-557 ◽  
pp. 411-414
Author(s):  
Bharat Krishnan ◽  
Sashi Kumar Chanda ◽  
Yaroslav Koshka
Keyword(s):  
Room Temperature ◽  
Free Exciton ◽  
Band Edge ◽  
Reverse Correlation ◽  
Band Edge Emission ◽  
Free Electron Concentration ◽  
Edge Emission ◽  
Room Temperature Photoluminescence ◽  
Mapping Techniques ◽  
Commercial Nitrogen

The room-temperature photoluminescence (RTPL) was investigated in commercial nitrogen-doped 4H-SiC substrates. In a typical RTPL spectrum of n-type 4H-SiC substrate, the ‘band-edge’ emission was similar to PL signatures that are typically attributed to free-exciton recombination in high-quality thick epitaxial layers. The origin of the deep-defect ‘red’ emission and its influence on recombination properties of SiC remain unclear. In most of the substrates in which the ‘red’ RTPL band was strong, clear reverse correlation between the ‘red’ and ‘band-edge’ RTPL intensities was observed. In contrast, direct correlation was observed between the ‘bandedge’ PL map and distribution of the net free electron concentration. There is a possibility that incorporation of nitrogen donors is influenced by (or influences) incorporation of lifetime-limiting deep defects.

scholarly journals Highly sensitive and room temperature detection of ultra-low concentrations of O3 using self-powered sensing elements of Cu2O nanocubes

2019 ◽  
Vol 1 (5) ◽  
pp. 2009-2017 ◽  
Author(s):  
E. Petromichelaki ◽  
E. Gagaoudakis ◽  
K. Moschovis ◽  
L. Tsetseris ◽  
T. D. Anthopoulos ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Room Temperature ◽  
Gas Sensing ◽  
Low Cost ◽  
New Class ◽  
Temperature Detection ◽  
Low Concentrations ◽  
Highly Sensitive ◽  
Self Powered ◽  
P Type

The fundamental development of the design of novel self-powered ozone sensing elements, operating at room temperature, based on p-type metal oxides paves the way to a new class of low cost, highly promising gas sensing devices.

Thermoelectric Properties of Ge-doped Cu3SbSe4

2011 ◽  
Vol 1314 ◽  
Author(s):  
Eric J. Skoug ◽  
Jeffrey D. Cain ◽  
Donald T. Morelli
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
State Of The Art ◽  
Unit Cell ◽  
Large Hole ◽  
Hole Effective Mass ◽  
Large Unit ◽  
Ternary Semiconductor ◽  
Large Unit Cell ◽  
P Type

ABSTRACTTernary variations of the II-VI zincblende semiconductors have received little attention for thermoelectric applications. Here we present the first systematic doping study on Cu3SbSe4, a zincblende-like ternary semiconductor with a unit cell four times larger than the parent II-VI compounds. The large unit cell of Cu3SbSe4 results in a low room temperature thermal conductivity (~3.0 W/m*K) and its large hole effective mass produces a Seebeck coefficient approaching 500 μV/K in the undoped compound. Our results show that Ge is an effective p-type dopant in Cu3SbSe4, and the power factor reaches nearly 16 μW/cm*K2 at 630K when 3% Ge is added, rivaling that of state-of-the-art thermoelectric materials at this temperature.

Thermoelectric Properties of Tl2Te-Sb2Te3 Pseudo-Binary System

2005 ◽  
Vol 886 ◽  
Author(s):  
Ken Kurisaki ◽  
Keita Goto ◽  
Atsuko Kosuga ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Binary System ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
State Of The Art ◽  
Electrical Performance ◽  
Low Thermal Conductivity ◽  
Maximum Value ◽  
P Type ◽  
Type Conduction

ABSTRACTPolycrystalline-sintered samples of thallium based substances, (Tl2Te)100−x(Sb2Te3)x (x= 0, 1, 5, 10), were prepared by melting Tl2Te and Sb2Te3 ingots followed by annealing in sealed quartz ampoules. The thermoelectric properties were measured from room temperature to around 600 K. The values of the Seebeck coefficient of all samples are positive, indicating a p-type conduction characteristic. The maximum value of the power factor is 6.53×10−4 Wm−1K−2 at 591 K obtained for x= 10 (Tl9SbTe6), which is about one order lower than those of state-of-the-art thermoelectric materials. All samples indicate an extremely low thermal conductivity, for example that of Tl2Te is approximately 0.35 Wm−1K−1 from room temperature to around 600 K. Although the electrical performance of the samples is not so good, the ZT value is relatively high due to the extremely low thermal conductivity. The maximum ZT value is 0.42 at 591 K obtained for Tl9SbTe6.

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