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1.
Low-leakage-current AIGaN/GaN HEMTs on Si substrates with partially Mg-doped GaN buffer layer by metal organic chemical vapor deposition
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High-performance low-leakage-current A1GaN/GaN high electron mobility transistors (HEMTs) on silicon (111) sub- strates grown by metal organic chemical vapor deposition (MOCVD) with a novel partially Magnesium (Mg)-doped GaN buffer scheme have been fabricated successfully. The growth and DC results were compared between Mg-doped GaN buffer layer and a unintentionally onμe. A 1μ m gate-length transistor with Mg-doped buffer layer exhibited an OFF-state drain leakage current of 8.3 × 10-8 A/mm, to our best knowledge, which is the lowest value reported for MOCVD-grown A1GaN/GaN HEMTs on Si featuring the same dimension and structure. The RF characteristics of 0.25-μ m gate length T-shaped gate HEMTs were also investigated. 相似文献
2.
Low-leakage-current AlGaN/GaN HEMTs on Si substrates with partially Mg-doped GaN buffer layer by metal organic chemical vapor deposition
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High-performance low-leakage-current AlGaN/GaN high electron mobility transistors(HEMTs) on silicon(111) substrates grown by metal organic chemical vapor deposition(MOCVD) with a novel partially Magnesium(Mg)-doped GaN buffer scheme have been fabricated successfully. The growth and DC results were compared between Mg-doped GaN buffer layer and a unintentionally one. A 1-μm gate-length transistor with Mg-doped buffer layer exhibited an OFF-state drain leakage current of 8.3 × 10-8A/mm, to our best knowledge, which is the lowest value reported for MOCVD-grown AlGaN/GaN HEMTs on Si featuring the same dimension and structure. The RF characteristics of 0.25-μm gate length T-shaped gate HEMTs were also investigated. 相似文献
3.
《中国科学:物理学 力学 天文学(英文版)》2010,(9)
AlGaN/GaN high electron mobility transistors(HEMTs) were grown on Si substrates by MOCVD.In the HEMT structure,a 1 μm GaN buffer layer was partially doped with Mg in an attempt to increase the resistivity and minimize the buffer leakage.The AlGaN/GaN HEMTs grown on undoped and partially Mg-doped GaN buffer layers were processed and the DC characteristics of the devices were characterized for comparing the effect of Mg doping.For the device with the partially Mg-doped GaN buffer layer,a lower drain leakage current density of 55.8 nA/mm,a lower gate leakage current density of 2.73 μA/mm,and a higher off-state breakdown voltage of 104 V were achieved with device dimensions Lg/Wg/Lgs/Lgd=1/10/1/1 μm,better than the device with the undoped GaN buffer layer,which has a higher drain leakage current density of 9.2 μA/mm,a higher gate leakage current density of 91.8 μA/mm,and a lower off-state breakdown voltage of 87 V with the same device dimensions. 相似文献
4.
Shoubin Xue Xing Zhang Ru Huang Huizhao Zhuang 《Applied Physics A: Materials Science & Processing》2009,94(2):287-291
ZnO thin films were first prepared on Si(111) substrates using a radio frequency magnetron sputtering system. Then the as-grown
ZnO films were annealed in oxygen ambient at temperatures of 700, 800, 900, and 1000°C , respectively. The morphologies of
ZnO films were studied by an atom force microscope (AFM). Subsequently, GaN epilayers about 500 nm thick were deposited on
the ZnO buffer layers. The GaN/ZnO films were annealed in NH3 ambient at 900°C. The microstructure, morphology and optical properties of GaN films were studied by x-ray diffraction (XRD),
AFM, scanning electron microscopy (SEM) and photoluminescence (PL). The results are shown, their properties having been investigated
particularly as a function of the ZnO layers. For better growth of the GaN films, the optimal annealing temperature of the
ZnO buffer layers was 900°C. 相似文献
5.
Yu. N. Buzynin Yu. N. Drozdov M. N. Drozdov A. Yu. Luk’yanov O. I. Khrykin A. N. Buzynin A. E. Luk’yanov E. I. Rau F. A. Luk’yanov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(11):1499-1503
New complex buffer layers based on a porous material have been developed for epitaxial growth of GaN films on Si substrates. The characteristics of gallium nitride heteroepitaxial layers grown on silicon substrates with new buffer layers by metal-organic vapor phase epitaxy are investigated. It is shown that the porous buffer layers improve the electric homogeneity and increase the photoluminescence intensity of epitaxial GaN films on Si substrates to the values comparable with those for reference GaN films on Al2O3 substrates. It is found that a fianite layer in a complex buffer is a barrier for silicon diffusion from the substrate into a GaN film. 相似文献
6.
High-quality gallium nitride (GaN) films were prepared on Si(111) substrates by sputtering post-annealing-reaction technique. XRD, XPS, and SEM measurement results indicate that polycrystalline GaN with hexagonal structure was successfully prepared. Intense room- temperature photoluminescence that peaked at 354 nm of the films is observed. The bandgap of these films has a blueshift with respect to bulk GaN. 相似文献
7.
《Physica E: Low-dimensional Systems and Nanostructures》2011,43(10):2518-2520
A photoconductivity (PC) of Si/Ge/Si structures with narrow Ge layer [thickness's 1.5 and 2 monolayers (ML)] on interband light intensity has been investigated for the different values of lateral voltage U, and temperature T. In contrast to the Si/Ge structure with 2 ML, where only monotonous PC growth was registered, for the 1.5 ML structure a stepped and a fluctuated PC were observed. These PC features are explained by a percolation of photoexcited carriers via the localized states induced by one monolayer scale Si/Ge interface roughnesses. 相似文献
8.
Zinc oxide (ZnO) thin films were grown on Si (1 0 0) substrates by pulsed laser deposition (PLD) using two-step epitaxial growth method. Low temperature buffer layer (LTBL) was initially deposited in order to obtain high quality ZnO thin film; the as-deposited films were then annealed in air at 700 °C. The effects of LTBL and annealing treatment on the structural and luminescent properties of ZnO thin film were investigated. It was found that tensile strain was remarkably relaxed by employing LTBL and the band-gap redshifted, correspondingly. The shift value was larger than that calculated from band-gap theories. After annealing treatment, it was found that the annealing temperature with 700 °C has little influence on strains of ZnO films with LTBLs other than directly deposited film in our experiments. Interestingly, the different behaviors in terms of the shift of ultraviolet (UV) emission after annealing between films with and without buffer were observed, and a tentative explanation was given in this paper. 相似文献
9.
V. V. Bel’kov Yu. V. Zhilyaev G. N. Mosina S. D. Raevskii L. M. Sorokin M. P. Shcheglov 《Physics of the Solid State》2000,42(9):1606-1609
The structure of bulk GaN layers grown on (0001) sapphire substrates by vapor-phase epitaxy has been studied by x-ray diffraction and transmission electron microscopy (TEM). It is found that these layers contain grown-in and screw dislocations. The dislocation density decreases away from the interface. The effect of an amorphous buffer layer on the formation of the initial GaN layer and, thus, on the degree of perfection of gallium nitride layers is elucidated. A model of generating grown-in dislocations and the relaxation mechanism of misfit stresses are proposed. 相似文献
10.
A detailed analysis of the thermal strain relaxation in GaAs/Ge/Si structures by means of crack formation is presented. The study was performed through optical microscopy and photoluminescence measurements. The as grown epilayers were found to be in a metastable state with respect to crack formation. Repeated thermal cycling increased the crack density up to an asymptotic limit. The thermal strain is not fully relaxed even near to the asymptotic crack density. 相似文献
11.
The influence of AlN/GaN superlattice intermediate layer on the properties of GaN grown on Si(111) substrates
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AlN/GaN superlattice buffer is inserted between GaN epitaxial layer
and Si substrate before epitaxial growth of GaN layer. High-quality
and crack-free GaN epitaxial layers can be obtained by inserting
AlN/GaN superlattice buffer layer. The influence of AlN/GaN
superlattice buffer layer on the properties of GaN films are
investigated in this paper. One of the important roles of the
superlattice is to release tensile strain between Si substrate and
epilayer. Raman spectra show a substantial decrease of in-plane
tensile strain in GaN layers by using AlN/GaN superlattice buffer
layer. Moreover, TEM cross-sectional images show that the densities
of both screw and edge dislocations are significantly reduced. The
GaN films grown on Si with the superlattice buffer also have better
surface morphology and optical properties. 相似文献
12.
Manoj Kumar Hiroto Sekiguchi Hiroshi Okada Akihiro Wakahara 《Applied Physics A: Materials Science & Processing》2013,112(4):847-853
A report on the fabrication and characterization of high performance conventional and ring-shaped AlGaN/GaN Schottky barrier diode on Si is presented. The resulting device exhibited low leakage current, which led to a detectivity performance of 3.48×1013 and 1.76×1013 cm?Hz1/2 W?1, respectively, for both conventional and ring-shaped Schottky diode. The differential resistances of both devices were obtained at approximately 1.37×1012 and 1.41×1013 Ω, respectively. The zero bias peak responsivities of conventional and ring-shaped Schottky diodes were estimated to be 3.18 and 2.08 A?cm?2/W, respectively. The typical UV to visible rejection ratio was observed over three orders of magnitude at zero bias. The C–V measurements was used to calculate and analyze the polarization sheet charge density of the AlGaN barrier layer by using self-consistently solving Schrodinger’s and Poisson’s equations. It is demonstrated that the ring shape of the Schottky barrier has higher polarization sheet charge density, which has the consequence that the Schottky shape has influence on the strain of the AlGaN barrier layer. 相似文献
13.
The thermal stability of SiGe films on an ultra thin Ge buffer layer on Si fabricated at low temperature has been studied. The microstructure and morphology of the samples were investigated by high-resolution X-ray diffraction, Raman spectra and atomic force microscopy, and using a diluted Secco etchant to reveal dislocation content. After thermal annealing processing, it is observed that undulated surface, threading dislocations (TDs) and stacking faults (SFs) appeared at the strained SiGe layer, which developed from the propagation of a misfit dislocation (MD) during thermal annealing, and no SFs but only TDs formed in strain-relaxed sample. And it is found that the SiGe films on the Ge layer grown at 300 °C has crosshatch-free surface and is more stable than others, with a root mean square surface roughness of less than 2 nm and the threading dislocation densities as low as ∼105 cm−2. The results show that the thermal stability of the SiGe films is associated with the Ge buffer layer, the relaxation extent and morphology of the SiGe layer. 相似文献
14.
VO2 thin films are grown on glass substrates by pulsed laser deposition using vanadium metal as a target. In this study, a ZnO thin film was used as a buffer layer for the growth of VO2 thin films on glass substrates. X-ray diffraction studies showed that the VO2 thin film had b-axis preferential orientation on a c-axis oriented ZnO buffer layer. The thickness of the ZnO buffer layer and the oxygen pressure during VO2 deposition were optimized to grow highly b-axis oriented VO2 thin films. The metal-insulator transition properties of the VO2 film samples were investigated in terms of infrared reflectance and electrical resistance with varying temperatures. 相似文献
15.
16.
《中国物理 B》2019,(2)
Polycrystalline gallium nitride(GaN) thin films were deposited on Si(100) substrates via plasma-enhanced atomic layer deposition(PEALD) under optimal deposition parameters. In this work, we focus on the research of the GaN/Si(100)interfacial properties. The x-ray reflectivity measurements show the clearly-resolved fringes for all the as-grown GaN films, which reveals a perfectly smooth interface between the GaN film and Si(100), and this feature of sharp interface is further confirmed by high resolution transmission electron microscopy(HRTEM). However, an amorphous interfacial layer(~ 2 nm) can be observed from the HRTEM images, and is determined to be mixture of Ga_xO_y and GaN by xray photoelectron spectroscopy. To investigate the effect of this interlayer on the GaN growth, an AlN buffer layer was employed for GaN deposition. No interlayer is observed between GaN and AlN, and GaN shows better crystallization and lower oxygen impurity during the initial growth stage than the GaN with an interlayer. 相似文献
17.
K.P. Homewood W.P. Gillin R.E. Pritchard W.S. Truscott K.E. Singer 《Superlattices and Microstructures》1990,7(4)
Strained 100 Å GaAsSb quantum wells in GaAs, grown by Molecular Beam Epitaxy have been subjected to thermal anneals up to a temperature of 950°C and for times varying from a few seconds to several minutes. The interdiffusion on the group V sublattice has been monitored using photoluminescence of the ground state emissions from the quantum well. We have made measurements on undoped and both p and n, Be and Si, doped structures. The intermixing is observed to be strongly non-linear. Doping is found to reduce the interdiffusion. 相似文献
18.
Growth of high quality InSb thin films on GaAs substrates by molecular beam epitaxy method with AlInSb/GaSb as compound buffer layers
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A series of In Sb thin films were grown on Ga As substrates by molecular beam epitaxy(MBE).Ga Sb/Al In Sb is used as a compound buffer layer to release the strain caused by the lattice mismatch between the substrate and the epitaxial layer,so as to reduce the system defects.At the same time,the influence of different interface structures of Al In Sb on the surface morphology of buffer layer is explored.The propagation mechanism of defects with the growth of buffer layer is compared and analyzed.The relationship between the quality of In Sb thin films and the structure of buffer layer is summarized.Finally,the growth of high quality In Sb thin films is realized. 相似文献
19.
Lam. H. Nguyen T. K. Nguyen-Duc V. Le Thanh F. A. d'Avitaya J. Derrien 《Physica E: Low-dimensional Systems and Nanostructures》2004,23(3-4):471
Single and stacked layers of Ge/Si quantum dots were grown in SiO2 windows patterned by electron-beam lithography on oxidized Si (0 0 1) substrates. The growth of a silicon buffer layer prior to Ge deposition is found to be an additional parameter for adjusting the Ge-dot nucleation process. We show that the silicon buffer layer evolves towards [1 1 3]-faceted pyramids, which reduces the area of the topmost (0 0 1) surface available for Ge nucleation. By controlling the top facet area of the Si buffer layers, only one dot per circular window and a high cooperative arrangement of dots on a striped window can be achieved. In stacked layers, the dot homogeneity can be improved through the adjustment of the Ge deposited amount in the upper layers. The optical properties of these structures measured by photoluminescence spectroscopy are also reported. In comparison with self-assembled quantum dots, we observed, both in single and stacked layers, the absence of the wetting-layer component and an energy blue shift, confirming therefore the dot formation by selective growth. 相似文献