Complete composition tunability of InGaN nanowires using a combinatorial approach. Nat Mater 6:951

Department of Chemistry, University of California, Berkeley, CA 94720, USA.
Nature Materials (Impact Factor: 36.5). 01/2008; 6(12):951-6. DOI: 10.1038/nmat2037
Source: PubMed
The III nitrides have been intensely studied in recent years because of their huge potential for everything from high-efficiency solid-state lighting and photovoltaics to high-power and temperature electronics. In particular, the InGaN ternary alloy is of interest for solid-state lighting and photovoltaics because of the ability to tune the direct bandgap of this material from the near-ultraviolet to the near-infrared region. In an effort to synthesize InGaN nitride, researchers have tried many growth techniques. Nonetheless, there remains considerable difficulty in making high-quality InGaN films and/or freestanding nanowires with tunability across the entire range of compositions. Here we report for the first time the growth of single-crystalline In(x)Ga(1-x)N nanowires across the entire compositional range from x=0 to 1; the nanowires were synthesized by low-temperature halide chemical vapour deposition and were shown to have tunable emission from the near-ultraviolet to the near-infrared region. We propose that the exceptional composition tunability is due to the low process temperature and the ability of the nanowire morphology to accommodate strain-relaxed growth, which suppresses the tendency toward phase separation that plagues the thin-film community.

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    • "One-dimensional (1D) nanostructures, such as nanorods [11,12], nanotubes [13e16], and nanowires [17,18], which have smaller diffusion distance of carriers and larger surface areas, are expected to have improved charge separation, charge transport, and light absorption properties compared to TiO 2 thin films with a planar structure. The methods to fabricate 1D TiO 2 nanostructures include colloidal synthesis [19,20], electrodeposition [21] , organometallic chemical vapor deposition (OMCVD) [22,23], chemical vapor deposition (CVD) [24,25], oblique-angle deposition (OAD) [11], hydrothermal processes [26,27]. Besides, one unique method for the fabrication and tailoring of nanostructured materials is via ion beam modification [28]. "
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    • "To overcome these problems, alternative methods of band gap tuning in GaN through equibiaxial in-plain strains have been proposed re- cently [4] as a method of " strain engineering " . In the context of GaN based nano-materials, nanowires, nanotubes, and nanospirals of GaN have been synthesized which showed great potential for fabricating wide-spectrum LEDs and other nano-scale devices567. In particular, a density functional theory (DFT) study in 2006 [8] predicted that when the layer number of (0001)-oriented WZ materials (e.g., AlN, BeO, GaN, SiC, ZnO, and ZnS) is small, the wurtzite structures transform into a new form of stable hexagonal graphite-like or hexagonal boron nitride (BN)-like structure. "
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    • "High vacuum chemical vapour deposition (HV-CVD) provides several interesting features involving addressable combinatorial experiments for fast optimization of thin films [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12], controlled growth of nanowires in a vapour–liquid–solid (VLS) process [13] [14] [15], and selective area growth exploiting laser [16] [17] [18], ion [19], or electron [20] beam assisted depositions. "
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