- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Growth of high quality AlN/sapphire templates with high growth rate using a medium-temperature layer
摘要： In this work, crack-free 3.3-μm-thick AlN ?lms with high crystalline quality and atomic smooth surfaces were achieved on sapphire substrates at a high growth rate of 2.9 μm/h. Double-axis x-ray rocking curves showed a full width at half maximum of 315 and 419 arc sec for (0002) and (101ˉ2) re?ections, respectively, corresponding to a total threading dislocation (TD) density of 9.79 × 10^8 cm^-2. Cracks were suppressed and crystalline quality was improved by introducing a medium-temperature (MT) layer. It was found that the density of both screw- and edge-type TDs could be signi?cantly reduced by introducing the MT-AlN layer under appropriate temperature. The crystalline improvement is attributed to the delayed coalescence of the AlN islands and higher probability for the annihilations of TDs by the MT-AlN layer under appropriate temperature. This method provides a promising way in growing practical thick AlN templates suitable for large-scale industrial production.
关键词： High growth rate,MOCVD,Crack-free,Medium-temperature layer,AlN
更新于2025-09-23 15:22:29
-
van der Waals Epitaxy of High-Mobility Polymorphic Structure of Mo <sub/>6</sub> Te <sub/>6</sub> Nanoplates/MoTe <sub/>2</sub> Atomic Layers with Low Schottky Barrier Height
摘要： High contact resistance between two-dimensional (2D) transition metal dichalcogenides (TMDs) and metal electrodes is a practical barrier for applications of 2D TMDs to conventional devices. A promising solution to this is polymorphic integration of 1T′-phase semi-metallic and 2H-phase semiconducting TMD crystals, which can lower the Schottky barrier of the TMDs. Here, we demonstrate the van der Waals epitaxy of density-controlled single isolated 1T′-Mo6Te6 nanoplates on 2H-MoTe2 atomic layers by using metal-organic chemical vapor deposition. Importantly, in situ grown 1T′-Mo6Te6 nanoplates significantly reduce the contact resistance of the 2H-MoTe2 atomic layers, providing a record high mobility of 1,139 cm2/Vs for Pd/1T′-Mo6Te6/2H-MoTe2 back-gated field-effect transistors (FETs), along with a low Schottky barrier height (q?b) of 8.7 meV. These results lead to the possibility of ameliorating the high contact resistance faced by other TMDs, and furthermore, offer polymorphic structures for realizing higher mobility TMD devices.
关键词： 1T′-2H polymorphs,MOCVD,transition metal dichalcogenides,Mo6Te6,MoTe2
更新于2025-09-23 15:22:29
-
Fabrication and characterization of Mg-doped ?μ-Ga2O3 solar-blind photodetector
摘要： In this work, Mg-doped ε-Ga2O3 (3.38 cation % of Mg) solar-blind photodetector is fabricated by using radio-frequency magnetron sputtering and metal-organic chemical vapor deposition methods on sapphire substrate. The results show that the Mg-doped ε-Ga2O3 thin film solar-blind photodetector exhibit a photo-to-dark current ratio of 1.68 102, responsivity of 77.2 mA/W, specific detectivity of 2.85 1012 Jones, and external quantum efficiency of 37.8 % at 5 V under 40 μW/cm2 254 nm ultraviolet light illumination, as well as the stable light switching property driven by different applied voltages and light intensities. The achieved Mg-doped ε-Ga2O3 solar-blind photodetector is promised to advance relevant developments of the metastable Ga2O3 optoelectronic devices.
关键词： MOCVD,solar-blind,Mg dopant,magnetron sputtering,ε-Ga2O3
更新于2025-09-23 15:21:01
-
[IEEE 2019 IEEE 14th Nanotechnology Materials and Devices Conference (NMDC) - Stockholm, Sweden (2019.10.27-2019.10.30)] 2019 IEEE 14th Nanotechnology Materials and Devices Conference (NMDC) - MOCVD synthesis of 2D saturable absorbers for pulsed fiber lasers
摘要： Nanolayers of MoSe2, NiO, VO2, Bi2Se3, Bi2Te3, Sb2Te3 compounds were fabricated using MOCVD technology. They were grown directly or mechanically deposited as a mixture with the polymer on the surface of tapered section of fibers. Tapers were fabricated by chemical etching. The deposition process was carried out in a special tubular quartz reactor with in-situ monitoring of optical transmission in the range of wavelength 1–1.65 μm. According to AFM, the deposited films consist of islands and occupy an insignificant part of the fiber surface. Tapers coated by 2D nanoislands were embedded in the ring circuit of an erbium fiber laser and tested as passive Q-switch. A transition from the continuous CW mode to the Q-switch mode was achieved for several samples with a taper diameter of less than 11 μm. For tapers of larger diameter the transition to the Q-switch mode was observed only when nanoislands of 2D compound were coated by polymer.
关键词： tapered fiber,2D materials,Q-swich,MOCVD method,erbium fiber ring lasers
更新于2025-09-23 15:21:01
-
Growth of AlGaN/GaN Heterostructure With Lattice-matched AlIn(Ga)N Back Barrier
摘要： AlGaN/GaN heterostructures were successfully grown with the AlIn(Ga)N back barrier at 900 ?C. However, the atomic composition of the AlIn(Ga)N layer was strongly dependent on the growth pressure, which resulted in a different lattice constant of the layer. The AlIn(Ga)N back barrier grown at 400 torr was almost lattice matched to the GaN layer. The AlGaN/GaN heterostructures with 10 and 15 nm-thick AlIn(Ga)N back barrier exhibited improved 2-DEG properties, compared to those of the conventional AlGaN/GaN heterostructure without the back barrier. The high electron mobility transistors (HEMTs) fabricated on the AlGaN/GaN heterostructure with a 15 nm-thick AlIn(Ga)N back barrier exhibited a very low off-state leakage current of ~ 2 x 10-7 A/mm which is about 1 order lower in magnitude than the value of the device without the back barrier. The AlIn(Ga)N back barrier is a promising candidate as an alternative to conventional AlGaN and InGaN back barrier.
关键词： HEMT,AlIn(Ga)N back barrier,AlGaN/GaN heterostructure,MOCVD
更新于2025-09-23 15:21:01
-
Study on Optical Properties and Waveguide Structure Optimization of Semiconductor Lasers with InGaAs Quantum Well
摘要： InGaAs quantum wells (QWs) are grown on GaAs substrates by metal-organic chemieal vapor deposition (MOCVD). Sample grown on substrates (100) oriented 2° off towards <111> exhibits relatively high photoluminescence (PL) intensity and narrow full-width at half-maximum (FWHM). Increasing growth rate leads to the enhancement of PL intensity and decrease of FWHM. Asymmetric waveguide layers are applied to reduce the confinement factor of base mode and increase the loss of higher-order mode.
关键词： MOCVD,waveguide structure,photoluminescence,InGaAs quantum wells,semiconductor lasers
更新于2025-09-23 15:19:57
-
[IEEE 2018 12th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM) - Smolenice (2018.10.21-2018.10.24)] 2018 12th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM) - Determination of Secondary-Ions Yield in SIMS Depth Profiling of Si, Mg, and C Ions Implanted Gan Epitaxial Layers
摘要： In this paper, we investigated the optical and electrical properties of InGaN/GaN multiple quantum well (MQW) structures grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD). The samples were characterized using photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), and Hall effect measurements. The results show that the In composition and well width significantly affect the emission wavelength and carrier concentration. The highest internal quantum efficiency (IQE) of 45% was achieved for the sample with 15% In and 3 nm well width at room temperature. These findings are crucial for the development of high-efficiency light-emitting diodes (LEDs) in the visible range.
关键词： MOCVD,MQW,LED,photoluminescence,InGaN
更新于2025-09-19 17:15:36
-
Correlation Between Two-Dimensional Electron Gas Mobility and Crystal Quality in AlGaN/GaN High-Electron-Mobility Transistor Structure Grown on 4H-SiC
摘要： We investigated the correlation between the crystal quality and two-dimensional electron gas (2DEG) mobility of an AlGaN/GaN high-electron-mobility transistor (HEMT) structure grown by metal-organic chemical vapor deposition. For the structure with an AlN nucleation layer grown at 1100 °C, the 2DEG mobility and sheet carrier density were 1627 cm2/V·s and 3.23 × 1013 cm?2, respectively, at room temperature. Further, it was confirmed that the edge dislocation density of the GaN buffer layer was related to the 2DEG mobility and sheet carrier density in the AlGaN/GaN HEMT.
关键词： MOCVD,2DEG,Mobility,AlGaN/GaN HEMT,Carrier Density,Edge and Screw Dislocation
更新于2025-09-19 17:15:36
-
Influence of the GaAs crystals diffusion in the shift towards low energies in the photoluminescence emission band of the GaN/GaNbuffer/GaAs structure
摘要： GaN buffer layers were obtained by nitridation of GaAs substrates and GaN upper layers were growth by MOCVD to make the GaN/GaNbuffer/GaAs structure. It was observed GaAs crystals diffusion in GaN upper layer from buffer layer, when the growth temperature reach 900 °C. Photoluminescence spectrum showed the decrease in the maximum energy from 3.2 eV (381 nm) to 2.9 eV (414 nm) with contributions in 2.6 eV (462 nm) and 2.5 eV (487 nm) related to GaAs crystals diffused in GaN upper layer and hydrogen impurities respectively, which induce extended defects in the lattice. It is considered that the temperature and the growth method of GaN buffer layer, influences the photoluminescence emission of the GaN upper layer, shifting its maximum energy to low energies. X-ray diffraction patterns and transmission electron microscopy micrographs support the presence of GaAs in the GaN upper layer of the GaN/GaNbuffer/GaAs structure obtained at 900 °C. The decrease of GaAs crystal diffusion in the GaN upper layer is observed, when its growth temperature increases from 900 to 1000 °C, with a maximum energy of 3.2 eV (381 nm).
关键词： MOCVD,Buffer layer,Diffusion,Nitridation
更新于2025-09-19 17:15:36
-
<i>In situ</i> passivation of GaAsSb nanowires for enhanced infrared photoresponse
摘要： Surface passivation of semiconductor nanowires (NWs) is important for their optoelectronic properties and applications. Here, the in situ passivation effect of an epitaxial InP shell and the corresponding photodetector performance is experimentally studied. Compared with the unpassivated GaAsxSb1-x core-only NWs, the GaAsxSb1-x/InP core/shell NWs have shown much stronger photoluminescence and cathodoluminescence intensities. Correspondingly, the fabricated single GaAsxSb1-x/InP core/shell NW photodetector shows a responsivity of 325.1 A/W (@ 1.3 μm and 1.5 V) that is significantly enhanced compared to that of single GaAsxSb1-x core-only NW photodetectors (143.5 A/W), with a comparable detectivity of 4.7×1010 and 5.3×1010 cm√Hz/W, respectively. This is ascribed to the enhanced carrier mobility and carrier concentration by the in situ passivation, which lead to both higher photoconductivity and dark-conductivity. Our results show that in situ passivation is an effective approach for performance enhancement of GaAs1-xSbx NW based optoelectronic devices.
关键词： semiconductor,surface passivation,infrared photodetector,GaAsSb,MOCVD,InP,nanowire
更新于2025-09-19 17:13:59