- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Selective Growth of Ordered Hexagonal InN Nanorods
摘要： Well-ordered and vertically aligned InN nanorods with high aspect ratio are synthetized by hydride vapor phase epitaxy (HVPE) using the selective area growth (SAG) approach. The growth occurs through the apertures of a SiNx masked Ga-polar GaN/c-Al2O3 template for adjusted growth temperature and V/III ratio. The nanorods exhibit a hexagonal shape without any rotation around the growth axis. The wurtzite structure and the high crystalline quality of InN nanorods are confirmed by X-ray diffraction (XRD) as well as by high-resolution transmission electron microscopy (HR-TEM). Only few stacking faults are identified at the bottom part of the nanorods. Photoluminescence (PL) displays an emission peak centered at 0.77 eV which agrees with the band gap of InN. These promising achievements, which go far beyond the existing InN growth limitations, pave the way towards the integration of pure InN in future devices
关键词： Selective Area Growth,Hydride Vapor Phase Epitaxy,Indium Nitride,Nanorods
更新于2025-11-21 11:03:13
-
3D GaN Fins as a Versatile Platform for a-Plane-Based Devices
摘要： GaN fins on GaN-on-sapphire templates are fabricated by continuous mode selective area metalorganic vapor phase epitaxy. The fins exhibit high aspect ratios and smooth nonpolar a-plane sidewalls with an ultra-low threading dislocation density of a few 105 cm?2 making them ideally suited for optoelectronic to electronic applications. A detailed analysis of the inner structure of GaN fins is provided by the help of marker layer experiments and correlation of results from fins fabricated under different growth conditions, leading to the development of a growth model to explain the final geometry and optical as well as electrical properties of these high aspect ratio fins. Distinctly different material properties for the central and outer parts of the fins are detected. Whereas the outer sidewalls represent high quality GaN surfaces with very low defect densities, a strong quenching of near band edge emission (NBE) in the central part of the fins is accompanied by heavy compensation of free electrons. A possible explanation is the incorporation of excessive point defects, like intrinsic defects or carbon impurity. The sidewall regions, however, prove to be highly suitable for device applications due to their strong NBE emission, low dislocation density, and high free carrier concentration.
关键词： marker layers,threading dislocation density,GaN fins,selective-area MOVPE,a-plane sidewalls
更新于2025-09-23 15:22:29
-
Selective Area Deposition of Hot Filament CVD Diamond on 100 mm MOCVD Grown AlGaN/GaN Wafers
摘要： A new technique is reported for selective growth of polycrystalline diamond by hot filament chemical vapor deposition (HFCVD) on AlGaN/GaN-on-Si (111) wafers without degradation of the underlying layers. Selective diamond seeding is accomplished by dispersing nano-diamond seeds in photoresist and patterned lithographically prior to HFCVD growth. A thin layer of plasma enhanced CVD SiNx, deposited prior to seeding and diamond deposition, was found to be essential to protect the AlGaN/GaN wafer. Methane concentration of 3.0% was used to achieve increased diamond growth rate and faster surface coverage. Excellent selectivity and minimal AlGaN surface damage were achieved due to the protective layer and faster surface coverage with increased methane concentration. Damage mitigation was confirmed by comparison of atomic force microscopy, x-ray diffraction, and Raman spectroscopy, each conducted before and after diamond deposition, and by SEM images of the final structures.
关键词： 2DEG,Reciprocal space mapping,III-Nitride,SiNx,Selective area deposition,CVD diamond,Photolithography,GaN decomposition
更新于2025-09-23 15:22:29
-
The morphology evolution of selective area wet etched commercial patterned sapphire substrates
摘要： Patterned sapphire substrates (PSS) have been widely used to enhance the light output power of light emitting diodes (LEDs). The morphology and shape of the PSS have a great influence on the performance of the LEDs. In this work, commercial PSS is reprocessed utilizing selective-area wet etching approach, in which selective-area SiO2 mask is fabricated through partial exposure lithography instead of conventional overlay lithography. By precisely controlling the exposure time, the etching process can be controlled to take place only on the top of the PSS. Various surface morphology including pyramid, volcano, clover and closed-packaged inverted pyramid can be attained from the evolution of the selective-area etched PSS. The mechanism of the selective-area etched sapphire is correlated to the slant angle of the pattern surface and the SiO2 mask pattern.
关键词： Wet etching,Selective-area,Patterned sapphire substracte
更新于2025-09-23 15:22:29
-
High-voltage regrown nonpolar m-plane vertical p-n diodes: A step toward future selective-area-doped power switches
摘要： We report high-voltage regrown nonpolar m-plane p-n diodes on freestanding GaN substrates. Secondary-ion mass spectroscopy (SIMS) measurements indicate O and Si spikes at the regrowth interfaces with maximum concentration ~ 5×1017 cm-3, which is similar to previously published c-plane studies. A high blocking voltage of 540 V at ~ 1 mA/cm2 (corresponding to an electric field of E ~ 3.35 MV/cm), turn-on voltages between 2.9-3.1 V, specific on-resistance of 1.7 mΩ.cm2 at 300 A/cm2, and a minimum ideality factor of 1.7 were obtained for the regrown diodes. Our results suggest that Si, O and C interfacial impurity levels up to 2×1017 cm-3, 8×1017 cm-3, and 1×1019 cm-3, respectively, at the metallurgical junction of m-plane p-n diodes do not result in very early breakdown in the reverse bias, although the off-state leakage current in forward bias is affected. The impact of growth interruption/regrowth on diode performance is also investigated.
关键词： Selective-area doping,GaN,Specific on-resistance,Impurity incorporation,Avalanche breakdown,Leakage currents,Ideality factor,Nonpolar,SIMS,Vertical p-n diodes
更新于2025-09-23 15:22:29
-
Realization of ultra-high quality InGaN platelets to be used as relaxed templates for red microLEDs
摘要： In this work, arrays of predominantly relaxed InGaN platelets with indium contents of up to 18%, free from dislocations and offering a smooth top c-plane, are presented. The InGaN platelets are grown by metal-organic vapor phase epitaxy on a dome-like InGaN surface formed by chemical mechanical polishing of InGaN pyramids defined by six equivalent {1011} planes. The dome-like surface is flattened during growth, through the formation of bunched steps, which are terminated when reaching the inclined {1011} planes. The continued growth takes place on the flattened top c-plane with single bilayer surface steps initiated at the six corners between the c-plane and the inclined {1011} planes, leading to the formation of high quality InGaN layers. The top c-plane of the as-formed InGaN platelets can be used as a high quality template for red microLEDs.
关键词： selective area growth,InGaN,template,chemical mechanical polishing,vapor phase epitaxy,microLEDs
更新于2025-09-23 15:21:01
-
p+ polycrystalline silicon growth via hot wire chemical vapour deposition for silicon solar cells
摘要： Hot wire chemical vapour deposition (HWCVD) is explored as a way of growing boron-doped silicon for photovoltaic devices. Deposition temperatures are measured using a custom-built monitoring system for two different filament configurations within the HWCVD tool. A refined fabrication process is presented, using an altered filament arrangement, that currently provides a maximum deposition temperature of 535 oC, for growing boron-doped silicon films via HWCVD, with the inclusion of a short post-deposition anneal at 800 oC for 2 minutes. Transmission electron microscopy reveals improvements in interfacial quality, as well as larger grains present after post-annealing treatments. In addition, re-crystallisation of as-deposited amorphous Si films under a short anneal is confirmed using Raman spectroscopy. The enhancements in morphology translate to a boost in current rectification based on our dark current-voltage measurements. This is further supported by secondary-ion mass spectrometry analysis, presenting p+ properties with uniform doping in the 1021 cm-3 region.
关键词： Selective area electron diffraction,Crystallisation,Emitter,Hot wire chemical vapour deposition,Silicon solar cells,Transmission electron microscopy
更新于2025-09-23 15:19:57
-
Selective area laser-assisted doping of SiC thin films and blue light electroluminescence
摘要： Laser-assisted doping combined with annealing technique is used in selective areas to form a p–n junction on a SiC thin film grown by the pulsed laser deposition on a Si substrate at a temperature of 800 °C. This approach in an aluminum chloride solution and a phosphoric solution has resulted in p-SiC/n-Si and n-SiC/p-Si hetero-structures, respectively. Further, a functional in-plane p–n junction is realized side-by-side on the post-deposited SiC thin film. I–V characteristics by two probe technique showed the p–n diode characteristics. Blue light (400 nm) electroluminescence from the p–n junction on SiC thin film was observed in the forward biased condition. Further, an improvement in the I–V reverse characteristics was observed by illuminating the p–n SiC thin film with green/blue light.
关键词： pulsed laser deposition,laser assisted doping,SiC thin film,electroluminescence,silicon carbide,selective area doping
更新于2025-09-23 15:19:57
-
Submicron fulla??color LED pixels for microdisplays and microa??LED main displays
摘要： We demonstrate a bottom-up approach to the construction of micro-LEDs as small as 150 nm in lateral dimension. Molecular beam epitaxy (MBE) is used to fabricate such nanostructured LEDs from InGaN, from the blue to red regions of the spectrum, providing a single material set useful for an entire RGB display.
关键词： nanowire,light-emitting diode,selective area growth,GaN,quantum dot,display
更新于2025-09-23 15:19:57
-
Phase-coherent transport in selectively grown topological insulator nanodots
摘要： Oxidized Si(111) substrates were pre-structured by electron beam lithography and used as a substrate for the selective growth of three-dimensional topological insulators (TI) by molecular beam epitaxy. The patterned holes were filled up by the TI, i.e. Sb2Te3 and Bi2Te3, to form nanodots. Scanning electron microscopy and focused ion beam cross-sectioning was utilized to determine the morphology and depth profile of the nanodots. The magnetotransport measurements revealed universal conductance fluctuations originating from electron interference in phase-coherent loops. We find that these loops are oriented preferentially within the quintuple layers of the TI with only a small perpendicular contribution. Furthermore, we found clear indications of an conductivity anisotropy between different crystal orientations.
关键词： phase-coherent transport,magnetotransport,selective area growth,topological insulators,molecular beam epitaxy
更新于2025-09-09 09:28:46