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[IEEE 2018 IEEE International Semiconductor Laser Conference (ISLC) - Santa Fe, NM (2018.9.16-2018.9.19)] 2018 IEEE International Semiconductor Laser Conference (ISLC) - High Power GaN-Based Blue Superluminescent Diode Exceeding 450 mW
摘要： We demonstrate a high-power blue emitting superluminescent diode (SLD) with a tilted-facet configuration. An optical power of 457 mW with a broad spectral bandwidth of 6.5 nm was obtained under pulsed current injection of 1A, leading to a large power-bandwidth product of ~2970 mW·nm.
关键词： gallium nitride,amplified spontaneous emission (ASE),superluminescent diode (SLD),laser diode
更新于2025-11-28 14:23:57
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Molybdenum Disulfide Catalytic Coatings via Atomic Layer Deposition for Solar Hydrogen Production from Copper Gallium Diselenide Photocathodes
摘要： We demonstrate that applying atomic layer deposition-derived molybdenum disulfide (MoS2) catalytic coatings on copper gallium diselenide (CGSe) thin film absorbers can lead to efficient wide band gap photocathodes for photoelectrochemical hydrogen production. We have prepared a device that is free of precious metals, employing a CGSe absorber and a cadmium sulfide (CdS) buffer layer, a titanium dioxide (TiO2) interfacial layer, and a MoS2 catalytic layer. The resulting MoS2/TiO2/CdS/CGSe photocathode exhibits a photocurrent onset of +0.53 V vs RHE and a saturation photocurrent density of ?10 mA cm?2, with stable operation for >5 h in acidic electrolyte. Spectroscopic investigations of this device architecture indicate that overlayer degradation occurs inhomogeneously, ultimately exposing the underlying CGSe absorber.
关键词： hydrogen evolution,molybdenum disulfide,photoelectrochemical water splitting,atomic layer deposition,copper gallium diselenide
更新于2025-11-19 16:56:35
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RbF post deposition treatment for narrow bandgap Cu(In,Ga)Se2 solar cells
摘要： Multi-junction solar cells are known to have a considerably increased efficiency potential over their typical single junction counterparts. In order to produce low cost and lightweight multi-junction devices, the availability of suitable narrow (<1.1 eV) bandgap bottom cells is paramount. A possible absorber for such a bottom cell is the Cu(In,Ga)Se2 (CIGS) compound semiconductor, one of the most efficient thin film materials to date. In this contribution we report on the RbF post deposition treatment of narrow bandgap CIGS absorbers grown with a single bandgap grading approach. We discuss the necessary deposition conditions and the observed improvements on solar cells performance. A certified record efficiency of 18.0 % for an absorber with 1.00 eV optoelectronic bandgap is presented and its suitability for perovskite/CIGS tandem devices is shown.
关键词： Post deposition treatment,Narrow bandgap,Tandem solar cells,Thin film solar cells,photovoltaics,Rubidium fluoride,Copper indium gallium selenide
更新于2025-11-14 17:28:48
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Detailed surface analysis of V-defects in GaN films on patterned silicon(111) substrates by metal–organic chemical vapour deposition
摘要： The growth mechanism of V-defects in GaN films was investigated. It was observed that the crystal faces of both the sidewall of a V-defect and the sidewall of the GaN film boundary belong to the same plane family of {10￣11}, which suggests that the formation of the V-defect is a direct consequence of spontaneous growth like that of the boundary facet. However, the growth rate of the V-defect sidewall is much faster than that of the boundary facet when the V-defect is filling up, implying that lateral growth of {10￣11} planes is not the direct cause of the change in size of V-defects. Since V-defects originate from dislocations, an idea was proposed to correlate the growth of V-defects with the presence of dislocations. Specifically, the change in size of the V-defect is determined by the growth rate around dislocations and the growth rate around dislocations is determined by the growth conditions.
关键词： transmission electron microscopy,threading dislocations,gallium nitride
更新于2025-11-14 17:04:02
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Tunable magnetic and fluorescent properties of Tb3Ga5O12 nanoparticles doped with Er3+, Yb3+, and Sc3+
摘要： In this study, we present the synthesis of Tb3Ga5O12 nanoparticles doped with Er3+, Yb3+, and Sc3+ ions, prepared using a co-precipitation method. These materials have well-defined magnetic-fluorescence properties. The effects of Yb3+ ion concentration on the structural characteristics, morphology, luminescence, and magnetic properties of the nanoparticles were investigated in detail using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, photoluminescence spectroscopy, and vibrating sample magnetometer measurements. Under 980-nm laser diode excitation, the nanoparticles displayed bright up-conversion luminescence, showing evidence of resonant energy transfer from the Yb3+ to Er3+ ions. Intense green and red emissions located at approximately 526, 548, and 656 nm were attributed to the radiant transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of Er3+, respectively. These observations indicate that Tb3Ga5O12:Er3+, Yb3+, Sc3+ magnetic–fluorescent bifunctional nanoparticles are promising materials for use in bioimaging and magnetic bio-separation applications.
关键词： magnetic properties,lanthanide-doped materials,nanoparticles,rare-earth metal,terbium gallium garnet (Tb3Ga5O12),up-conversion luminescence
更新于2025-11-14 15:26:12
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GaxSe10-x based solar cells: Some alternatives for the improvement in their performance parameters
摘要： We report on strategies that improve Se-derivative based solar cells performance. With this aim, a compact thin film based on ZnO nanoparticles is deposited onto fluorine doped tin oxide (FTO) as an electron-transport layer, in thermally evaporated GaxSe10-x based solar cells. ZnO nanoparticles films are synthesized by sol-gel process whereas GaxSe10-x material is obtained by mechanical alloying. Using current-voltage measurements, impedance spectroscopy, and capacitance-voltage profiling, device characteristics and performance limiting factors are revealed and discussed. Particularly, the use of ZnO nanoparticles results in improved device performance as well as long-term stability. In comparison to Se-only devices with the structure FTO/Se/Au (power conversion efficiency of 0.98%), under 100 mW/cm2 AM 1.5 G illumination the devices achieved a power conversion efficiency of 2.7% with the structure FTO/ZnO/GaSe9/Au (open circuit voltage of 0.71 V, short-circuit current of 7.9 mA/cm2). Hence, an increase of around 175% in the power conversion efficiency is obtained in comparison to Se-only devices. In addition, the effect of others parameters, like thickness of the active layer as well as the gallium contents in the alloy, are discussed.
关键词： Gallium selenide,Solar cells,ZnO nanoparticles,Electric modulus spectroscopy
更新于2025-10-22 19:40:53
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Structural and Optical Properties of AlN/GaN and AlN/AlGaN/GaN thin films on Silicon Substrate prepared by Plasma Assisted Molecular Beam Epitaxy (MBE)
摘要： In this study, the Aluminium Nitride/Gallium Nitride (AlN/GaN) layers and Aluminium Nitride/Aluminium Gallium Nitride/Gallium Nitride (AlN/AlGaN/GaN) layer heterostructures were successfully created using technique known as plasma-assisted molecular beam epitaxy (MBE) on silicon substrate. Gallium (7N) and Aluminium (6N5) of high purity were used to grow GaN, AlN and AlGaN respectively. The structural and optical properties of the prepared AlN/GaN and AlN/AlGaN/GaN layer heterostructures were investigated by means of atomic force microscope (AFM), X-ray diffraction (XRD), photoluminescence spectroscopy (PL) and Raman spectroscopy. AFM measurement demonstrated that the root mean square of surface roughness for AlN/GaN and AlN/AlGaN/GaN heterostructures are 3.677 nm and 10.333 nm respectively. XRD data indicated that the samples have typical diffraction pattern of hexagonal structure. Raman spectra revealed all four Raman-active modes present inside both samples. PL spectra data showed the yellow luminescence which corresponds to the deep energy levels due to imperfections of AlN did not appear. Thus, PL observation indicated that the thin film of AlN/GaN and AlN/AlGaN/GaN layers have good optical quality and looks promising for various target applications in optoelectronics, photovoltaic and radiofrequency applications.
关键词： silicon,thin film,MBE,Aluminium Nitride,Gallium Nitride,Aluminium Gallium Nitride
更新于2025-09-23 15:23:52
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Nanoscale GaN Epilayer Grown by Atomic Layer Annealing and Epitaxy at Low Temperature
摘要： Heteroepitaxy with large thermal and lattice mismatch between the semiconductor and substrate is a critical issue for high-quality epitaxial growth. Typically, high growth temperatures (>1000 °C) are required to achieve high-quality GaN epilayers by conventional metal?organic chemical vapor deposition. In this study, the high-quality GaN heteroepitaxy is realized by atomic layer annealing and epitaxy (ALAE) at a low growth temperature of 300 °C. The layer-by-layer, in situ He/Ar plasma treatment at a low plasma power was introduced in each cycle of atomic layer deposition to contribute the e?ective annealing e?ect for signi?cant enhancement of the GaN crystal quality. The Penning e?ect is responsible for signi?cant improvement of the GaN crystal quality due to the incorporation of He into the Ar plasma. The high-resolution transmission electron microscopy, nano-beam electron di?raction, and atomic force microscopy reveal a high-quality nanoscale single-crystal GaN heteroepitaxy and a very smooth surface. The full width at half-maximum of the X-ray rocking curve of the GaN epilayer is as low as 168 arcsec. The low-temperature ALAE technique is highly bene?cial to grow high-quality nanoscale GaN epilayers for sustainable, energy-saving, and energy-e?cient devices including high-performance solid-state lighting, solar cells, and high-power electronics.
关键词： Atomic layer annealing,Atomic layer deposition,Gallium nitride,Atomic layer epitaxy,Plasma treatment
更新于2025-09-23 15:23:52
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24.5: Back-Channel-Etched a-IGZO TFTs with TiO <sub/>2</sub> :Nb Protective Layer
摘要： A back-channel-etched (BCE) process for the fabrication of a-IGZO TFTs is demonstrated, in which conductive TiO2:Nb (TNO) thin film is used to serve as protective layer for the a-IGZO active layer. TNO film could excellently protect a-IGZO due to its ultra-small surface roughness. With treatment by N2O plasma + 200°C annealing, the conductive TNO can be converted into an insulator to serve as an in situ passivation layer. Besides, the TNO in the source–drain (S-D) region remain conductive due to the protection of S-D electrodes, which could be proved by the XPS results. Compare with the conventional device without TNO protective layer, the S-D parasitic resistance (RSD) of devices with 1 nm and 5 nm TNO is significantly reduced. The positive bias stress stability is improved as well for the devices with TNO in situ passivation layer.
关键词： amorphous indium gallium zinc oxide (a-IGZO),Nb doped TiO2 (TNO),thin film transistors (TFTs),back-channel-etched (BCE) process
更新于2025-09-23 15:23:52
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Tunable Wide-Bandwidth Resonators Based on Layered Gallium Sulfide
摘要： Wide-bandwidth and high-frequency operation are the two desired properties from resonators in a wide range of applications, such as communication devices, energy harvesters, inertial sensors, and electronic components. However, achieving both of these prerequisites along with detectable vibration amplitudes is very challenging. Herein, nano-electromechanical resonators based on layered gallium sulfide (GaS) are demonstrated. These resonators show resonance frequencies in the range of 10–25 MHz under ambient conditions and a bandwidth of hundreds of kilohertz, which can be simply tuned by predetermining the dimensions of the devices. Therefore, this study emphasizes that, in addition to excellent performances in electronic and optoelectronic applications, GaS can also be implemented as a high performance core element in nanoresonator applications.
关键词： electromechanical properties,wide-bandwidth resonators,gallium sulfide,2D materials
更新于2025-09-23 15:23:52