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High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs <sub/>1a??x</sub> Sb <sub/>x</sub> superlattice photodetector by MOCVD
摘要： We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1?xSbx superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77 K, the photodetector exhibits a peak responsivity of 0.70 A/W at 3.65 μm, corresponding to a quantum efficiency of 24% at zero bias without anti-reflection coating, with a 50% cutoff wavelength of 4.28 μm. With an R0A value of 3.2 × 105 Ω cm2 and a dark current density of 9.6 × 10?8 A/cm2 under an applied bias of ?20 mV at 77 K, the photodetector exhibits a specific detectivity of 2.9 × 1012 cm Hz1/2/W. At 150 K, the photodetector exhibits a dark current density of 9.1 × 10?6 A/cm2 and a quantum efficiency of 25%, resulting in a detectivity of 3.4 × 1011 cm Hz1/2/W.
关键词： specific detectivity,metal-organic chemical vapor deposition,type-II InAs/InAs1?xSbx superlattices,quantum efficiency,Zn-diffused planar mid-wavelength infrared photodetector
更新于2025-09-23 15:19:57
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Metal-Semiconductor-Metal ?μ-Ga2O3 Solar-Blind Photodetectors with a Record High Responsivity Rejection Ratio and Their Gain Mechanism
摘要： In recent years, Ga2O3 solar-blind photodetector (SBPD) has been attached great attention for its potential application in solar-blind imaging, deep space exploration, and confidential space communication, etc. In this work, we demonstrated an ultrahigh performance ε-Ga2O3 metal-semiconductor-metal (MSM) SBPD. The fabricated photodetectors exhibited record-high responsivity and fast decay time of 230 A/W and 24 ms, respectively, compared with MSM-structured Ga2O3 photodetectors reported to date. Additionally, the ε-Ga2O3 MSM SBPD presents ultrahigh detectivity of 1.2×1015 Jones with low dark current of 23.5 pA under the operation voltage of 6 V, suggesting its strong capability of detecting an ultraweak signal. The high sensitivity and wavelength selectivity of the photodetector were further confirmed by the record high responsivity rejection ratio (R250nm/R400nm) of 1.2×105. From the temperature-dependent electrical characteristics in the dark, the thermionic field emission and Poole-Frenkel emission were found to be responsible for the current transport in the low and high electric field regimes, respectively. In addition, the gain mechanism was revealed by the Schottky barrier lowering effect due to the defect states at the interface of metal contact and Ga2O3 or in the bulk of Ga2O3 based on current transport mechanism and density functional theory (DFT) calculation. These results facilitate a better understanding of ε-Ga2O3 photoelectronic devices and provide possible guidance for promoting their performance in future solar-blind detection applications.
关键词： rejection ratio,metal-organic chemical vapor deposition,ε-Ga2O3,responsivity,high-performance,solar-blind photodetector
更新于2025-09-19 17:13:59
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-Ga2O3 substrate enabled by self-assembled SiO2 nanospheres
摘要： To obtain high-quality GaN epitaxial ?lm on (?2 0 1) β-Ga2O3 substrate, periodic SiO2 nanosphere monolayer was self-assembled followed by inductively coupled plasma (ICP) etching. This periodic SiO2 nanosphere patterned Ga2O3 substrate (SiO2-NPGS) enables nanoscale epitaxial lateral overgrowth (NELOG) of GaN ?lm. Compared to planar Ga2O3 substrate, SiO2-NPGS shows great potential for epitaxial GaN with (0 0 0 2) and (1 0 ?1 2) full-width at half-maximum (FWHM) reduced from 555 to 388 arcsec, and 634 to 356 arcsec, respectively. Raman spectra also con?rm that the as-grown GaN ?lm on SiO2-NPGS is almost stress-free. The dislocation reduction is also observed by cross-sectional transmission electron microscope (TEM). The embedded SiO2-nanosphere blocks the dislocations and induces the GaN lateral overgrowth, thus leading to the signi?cant reduction of the threading dislocation densities. These ?ndings provide a new way for high quality stress-free GaN ?lm epitaxial growth on Ga2O3 substrate.
关键词： A3 Metal organic chemical vapor deposition,B1 SiO2 nanosphere,B1 Ga2O3,B1 GaN,A1 Nanoscale epitaxial lateral overgrowth
更新于2025-09-12 10:27:22
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Renewable and Sustainable Composites || Methodologies for Achieving 1D ZnO Nanostructures Potential for Solar Cells
摘要： One-dimensional (1D) nanostructures are generally used to describe large aspect ratio rods, wires, belts, and tubes. The 1D ZnO nanostructures have become the focus of research owing to its unique physical and technological significance in fabricating nanoscale devices. When the radial dimension of the 1D ZnO nanostructures decreases to some lengths (e.g., the light wavelength, the mean of the free path of the phonon, Bohr radius, etc.), the effect of the quantum mechanics is definitely crucial. With the large surface-to-volume ratio and the confinement of two dimensions, 1D ZnO nanostructures possess the captivating electronic, magnetic, and optical properties. Furthermore, 1D ZnO nanostructure’s large aspect ratio, an ideal candidate for the energy transport material, can conduct the quantum particles (photons, phonons, electrons) to improve the relevant technique applications. To date, many methods have been developed to synthesize 1D ZnO nanostructures. Therefore, methodologies for achieving 1D ZnO nanostructures are expressed, and the relevant potential application for solar cells are also present to highlight the attractive property of 1D ZnO nanostructures.
关键词： hydrothermal,nanostructures,one dimensional,ZnO,solar cell,chemical vapor transport and condensation (CVTC),vapor-liquid-solid (VLS),electrochemical,metal-organic chemical vapor deposition (MOCVD),chemical vapor deposition (CVD)
更新于2025-09-11 14:15:04
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Fabricating GaN-based LEDs on (?2 0 1) <i>β</i> -Ga <sub/>2</sub> O <sub/>3</sub> substrate via non-continuous/continuous growth between low-temperature undoped-GaN and high-temperature undoped-GaN in atmospheric pressure metal-organic chemical vapor deposition
摘要： This study demonstrates two approaches to the growth of GaN-based LEDs on (?2 0 1)-oriented β-Ga2O3 single crystal substrates using metal-organic CVD under atmospheric pressure. One approach induces non-continuous growth between low-temperature undoped-GaN (u-GaN) and high-temperature u-GaN, whereas the other approach induces continuous growth. We observed the following reduction in the FWHM of X-ray diffraction rocking curves: GaN (0 0 2) on (?2 0 1) β-Ga2O3 substrate (from 464 to 342 arcsec) and GaN (1 0 2) (from 886 to 493 arcsec). An LED with six pairs of InGaN/GaN multiple quantum wells was successfully fabricated on the (?2 0 1) β-Ga2O3 single crystal substrate.
关键词： metal-organic chemical vapor deposition,X-ray diffraction,β-Ga2O3 substrate,non-continuous/continuous growth,GaN-based LEDs
更新于2025-09-11 14:15:04
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Effects of N2 and NH3 plasma exposure on the surface topography of p-GaN under quasi-atmospheric pressure
摘要： We used atomic force microscopy to characterize the surface topography of p-GaN exposed to N2 and NH3 plasma under quasi-atmospheric pressure using a microwave-excited plasma source with a microstrip line structure. The exposure time was varied from 2 to 20 min at a substrate temperature of 700 °C. Under both N2 and NH3 plasma exposure for 2 min, the ridge-shaped features on the surface of as-grown p-GaN dulled immediately and the surface roughness decreased remarkably, whereas the atomic step structure of the surface was maintained. The step crossing and bunching of the surface disappeared with increasing exposure time to both types of plasma. However, increasing the NH3 plasma exposure time to 20 min led to the formation of pits and appearance of particles along the step edges, resulting in drastic roughening of the surface. Thus, GaN surfaces can be smoothed without the destruction of their step structures via moderate plasma exposure under quasi-atmospheric pressure, and these plasma sources could prospectively be used in metal-organic chemical vapor deposition systems for nitride semiconductor growth.
关键词： microwave-assisted plasma,surface topography,N2 and NH3 plasma,atomic force microscopy,metal organic chemical vapor deposition,GaN
更新于2025-09-09 09:28:46