Molecular beam epitaxy of InN nanowires on Si
TL;DR: In this paper, a growth study of the nucleation process of InN nanowires on Si(1.1) substrates using plasma assisted molecular beam epitaxy (PAMBE) was performed.
About: This article is published in Journal of Crystal Growth.The article was published on 2015-10-15. It has received 12 citations till now. The article focuses on the topics: Molecular beam epitaxy & Nanowire.
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TL;DR: It is found that the initial In droplet on the substrate is not only advantageous for the nucleation of the InN nanowire, but also favorable for the In atom equilibrium between theInitial In droplets and the direct In flux.
Abstract: The effects of the growth parameters on the uniformity and the aspect ratio of InN nanowires grown on Si(111) substrates have been studied systematically, and a modified quasi-equilibrium model is proposed. The growth temperature is of great importance for both the nucleation of the nanowires and the migration of In and N atoms, thus affecting the uniformity of the InN nanowires. In order to improve the uniformity of the InN nanowires, both traditional substrate nitridation and pre-In-droplet deposition have been implemented. It is found that the substrate nitridation is favorable for the nucleation of InN nanowires. However, the initial In atoms adhered to the substrate are insufficient to sustain the uniform growth of the InN nanowires. We have found that the initial In droplet on the substrate is not only advantageous for the nucleation of the InN nanowire, but also favorable for the In atom equilibrium between the initial In droplets and the direct In flux. Therefore, InN nanowires with a uniform aspect ratio and optimal diameter can be achieved. The results reported herein provide meaningful insights to understanding the growth kinetics during the InN nanowires growth, and open up great possibilities of developing high-performance group III-nitride-based devices.
18 citations
TL;DR: In this paper, the effect of employing hot filament as a localized ion source (LIS) on the structural, morphological and optical properties of thin InN thin films was investigated.
10 citations
TL;DR: In this article, the self-assembly of hexagonal InN micro-mushrooms on Si (111) substrates by molecular beam epitaxy is reported, and a detailed growth study along with SEM measurements reveals that an upside-down pendeoepitaxy mechanism underlies the formation of these structures.
9 citations
TL;DR: In this article, the authors review the recent progress made on the growth, characterization, and device applications of InN nanowires, which are free of surface electron accumulation and Fermi-level pinning.
Abstract: In this chapter, we review the recent progress made on the growth, characterization, and device applications of InN nanowires. Early research on InN nanowires is limited by their n-type degenerate characteristics, wherein the Fermi level is located deep in the conduction band, with the presence of high-density surface electrons. Recently, with the improved molecular beam epitaxy growth process, intrinsic and p-type InN nanowires have been realized, which are free of surface electron accumulation and Fermi-level pinning, providing great promise for a broad range of devices and applications.
9 citations
TL;DR: Real-time imaging during in situ environmental scanning electron microscopy experiment clearly demonstrates that the nanowire arrays form through a selective vaporization process with respect to the crystallography of wurtzite crystals.
Abstract: Direct transformation of bulk crystals to single-crystalline crystallographically oriented semiconductor nanowire arrays is presented. Real-time imaging during in situ environmental scanning electron microscopy experiment clearly demonstrates that the nanowire arrays form through a selective vaporization process with respect to the crystallography of wurtzite crystals. Due to the high quality of the prepared semiconductor nanowire arrays, photodetectors constructed from them can present superior optoelectronic performances.
9 citations
References
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TL;DR: In this article, the authors report the fabrication and dc characterization of a high electron mobility transistor (HEMT) based on a n−GaN−Al0.86N heterojunction.
Abstract: In this letter we report the fabrication and dc characterization of a high electron mobility transistor (HEMT) based on a n‐GaN‐Al0.14Ga0.86N heterojunction. The conduction in our low pressure metalorganic chemical vapor deposited heterostructure is dominated by two‐dimensional electron gas at the heterostructure interface. HEMT devices were fabricated on ion‐implant isolated mesas using Ti/Au for the source drain ohmic and TiW for the gate Schottky. For a device with a 4 μm gate length (10 μm channel opening, i.e., source‐drain separation), a transconductance of 28 mS/mm at 300 K and 46 mS/mm at 77 K was obtained at +0.5 V gate bias. Complete pinchoff was observed for a −6 V gate bias.
799 citations
TL;DR: Wurtzite InN films were grown on a thick GaN layer by metalorganic vapor phase epitaxy as discussed by the authors, and growth of a (0001)-oriented single crystalline layer was confirmed by Raman scattering, x-ray diffraction, and reflection high energy electron diffraction.
Abstract: Wurtzite InN films were grown on a thick GaN layer by metalorganic vapor phase epitaxy. Growth of a (0001)-oriented single crystalline layer was confirmed by Raman scattering, x-ray diffraction, and reflection high energy electron diffraction. We observed at room temperature strong photoluminescence (PL) at 0.76 eV as well as a clear absorption edge at 0.7–1.0 eV. In contrast, no PL was observed, even by high power excitation, at ∼1.9 eV, which had been reported as the band gap in absorption experiments on polycrystalline films. Careful inspection strongly suggests that a wurtzite InN single crystal has a true bandgap of 0.7–1.0 eV, and the discrepancy could be attributed to the difference in crystallinity.
692 citations
TL;DR: In this paper, the fundamental band gap for InN is shown to be near 0.8 eV and the band gap increases with increasing Ga content, which is well fit with a bowing parameter of ∼1.4 eV.
Abstract: High-quality wurtzite-structured In-rich In1−xGaxN films (0⩽x⩽0.5) have been grown on sapphire substrates by molecular beam epitaxy. Their optical properties were characterized by optical absorption and photoluminescence spectroscopy. The investigation reveals that the narrow fundamental band gap for InN is near 0.8 eV and that the band gap increases with increasing Ga content. Combined with previously reported results on the Ga-rich side, the band gap versus composition plot for In1−xGaxN alloys is well fit with a bowing parameter of ∼1.4 eV. The direct band gap of the In1−xGaxN system covers a very broad spectral region ranging from near-infrared to near-ultraviolet.
590 citations
TL;DR: In this article, the first successful P-GaN/n-InGaN+GaN double-heterostructure (DH) blue-light-emitting diodes (LEDs) were fabricated successfully for the first time.
Abstract: P-GaN/n-InGaN/n-GaN double-heterostructure (DH) blue-light-emitting diodes (LEDs) were fabricated successfully for the first time. The output power was 125 µW and the external quantum efficiency was as high as 0.22% at a forward current of 20 mA at room temperature. The peak wavelength and the full width at half-maximum (FWHM) of the electroluminescence (EL) were 440 nm and 180 meV, respectively. This value FWHM of was the smallest ever reported for blue GaN LEDs.
564 citations
TL;DR: In this article, the III-V nitrides were used as a high-performance photovoltaic material with open-circuit voltages up to 2.4V and internal quantum efficiencies as high as 60%.
Abstract: We experimentally demonstrate the III-V nitrides as a high-performance photovoltaic material with open-circuit voltages up to 2.4V and internal quantum efficiencies as high as 60%. GaN and high-band gap InGaN solar cells are designed by modifying PC1D software, grown by standard commercial metal-organic chemical vapor deposition, fabricated into devices of variable sizes and contact configurations, and characterized for material quality and performance. The material is primarily characterized by x-ray diffraction and photoluminescence to understand the implications of crystalline imperfections on photovoltaic performance. Two major challenges facing the III-V nitride photovoltaic technology are phase separation within the material and high-contact resistances.
560 citations