Atomically sharp catalyst-free wurtzite GaAs∕AlGaAs nanoneedles grown on silicon

Moewe, M.; Chuang, Linus C.; Crankshaw, S.; Chase, Chris; Chang-Hasnain, Connie J.

doi:10.1063/1.2949315

Cited by 111 publications

(98 citation statements)

References 21 publications

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“…Experimental results showed the bandgap of WZ phase is larger than that of ZB for GaAs [111][112][113], as well as for other material systems [114,115]. However for GaAs, contrary reports showing a smaller bandgap of the WZ phase than the ZB phase are also available [112,116,117]. In addition to the differences in the bandgap, the linear polarization of the PL emission was found to be strongly dependent on the crystal phase of the NWs.…”

Section: Extended Defectsmentioning

confidence: 72%

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

et al. 2014

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This thesis deals with the growth of GaAs nanowires (NWs) by molecular beam epitaxy (MBE) using vapor-liquid-solid method on various substrates including GaAs(111)B, Si(111) and graphene. The growth of the NWs on GaAs substrates was carried out by Au-catalyzed technique, whereas the growths on Si and graphene substrates were carried out using self-catalyzed technique that has been the main focus of this thesis. The long-term goal of this work was to produce p-n radial junction GaAs NWs for solar cell applications.Necessary conditions were established for obtaining vertical self-catalyzed GaAs NWs on Si(111), which is reproducible from run-to-run. One of the major issues in these NWs grown by both Au-and self-catalyzed techniques is their crystal structure. The Au-catalyzed GaAs NWs usually adopt a wurtzite (WZ) crystal phase, whereas the self-catalyzed NWs a zinc blende (ZB) phase. However, in both the cases the NWs contain stacking faults, rotational twins or/and a mixed crystal phase. The ZB and WZ phases show different optical properties, and one phase might be favored over other for certain applications. Therefore the crystal phase was controlled within single NWs by tuning the V/III ratio and introducing GaAsSb inserts. The change of the crystal phases was correlated with the change in the contact angle of the Ga droplet.Since the discovery of graphene, an ultra-thin two-dimensional material, the research on graphene has become an active field in recent years due to its remarkable properties including excellent electrical and thermal conductivities, mechanical strength and flexibility, and optical transparency. By growing the semiconductor NWs on graphene, a completely new hybrid system can be envisioned where the unique properties of both NWs and graphene can be utilized. Therefore we established a method for the growth of semiconductor NWs on graphene by demonstrating epitaxial growth of vertical GaAs and InAs NWs on different graphitic substrates.Core-shell heterostructure, doping, optical properties, and position controlled growth of self-catalyzed GaAs NWs were investigated. Growth of GaAs/GaAsSb coreshell NWs where the Sb content was tuned from about 10% -70% was studied. The effect of growth temperature and the Sb flux on the morphology of GaAsSb shell was investigated. In addition, by utilizing the core-shell geometry where the shell copies the crystal phase of the core, WZ phase of GaAsSb was demonstrated. Successful p-type doping of GaAs core using Be as dopant, and n-type doping of GaAs shell using Si and Te as dopants were achieved. To investigate the optical properties, GaAs/AlGaAs coreshell NWs were grown with different V/III ratios during the core growth. The NWs grown with high V/III ratio, despite containing a higher density of twinned ZB and WZ GaAs with SFs, were found to have superior optical quality as compared to the NWs grown with low V/III ratio that contain pure ZB GaAs. The observed V/III ratio dependent optical quality was correlated to the intrinsic defects such as As vac...

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Section: Extended Defectsmentioning

confidence: 72%

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

et al. 2014

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“…Surrounding the nanopillar, InGaAs evolves into polycrystalline thin film. The same polyInGaAs layer is also observed in the growth of (In)GaAs nanostructures on (111)-Si and sapphire substrates, [13][14] indicating that the formation of such layer is likely due to the low growth temperature and high lattice mismatch rather than crystallinity of the substrate. This polycrystalline layer grows simultaneously with the single crystalline structure throughout the entire growth process and restricts the pillar base from expanding, thus resulting in inverse tapering at the root, as seen in Figure 2(a) and (c).…”

Section: Manuscript Textmentioning

confidence: 77%

Single Crystalline InGaAs Nanopillar Grown on Polysilicon with Dimensions beyond the Substrate Grain Size Limit

Tran

et al. 2013

Nano Lett.

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Monolithic integration of III-V optoelectronic devices with materials for various functionalities inexpensively is always desirable. Polysilicon (poly-Si) is an ideal platform because it is dopable and semi-conducting and can be deposited and patterned easily on a wide range of low cost substrates. However, the lack of crystalline coherency in poly-Si poses an immense challenge for high-quality epitaxial growth. In this work, we demonstrate, for the first time, direct growth of micron-sized InGaAs/GaAs nanopillars on polysilicon. Transmission electron microscopy shows that the micron-sized pillars are single-crystalline and single Wurzite-phase, far exceeding the substrate crystal grain size ~100nm. The high quality growth is enabled by the unique tapering geometry at the base of the nanostructure, which reduces the effective InGaAs/Si contact area to < 40 nm in diameter. The small footprint not only reduces stress due to lattice mismatch but also prevents the nanopillar from nucleating on multiple Si crystal grains. This relaxes the grain size requirement for poly-Si, potentially reducing the cost for poly-Si deposition. Lasing is achieved in the as-grown pillars under optical pumping, attesting their excellent crystalline and optical quality. These promising results open up a pathway for low-cost synergy of optoelectronics with other technologies such as CMOS integrated circuits, sensing, nanofluidics, thin film transistor display, photovoltaics, etc.

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“…Notably, these conditions are favourable for CMOS devices, raising the possibility of integrating III-V PICs with silicon electronics. Additional details on the nanomaterial synthesis process can be found in both references 24,27 and the Methods section. Figure 1b displays a scanning electron microscope (SEM) image of a single as-grown InGaAs nanoresonator, showcasing the hexagonal nanopillar geometry that provides a natural optical cavity.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, we showed that this is possible via growth of InGaAs nanopillars on silicon. Though they first nucleate as nanoneedles only a few nanometres wide 24,25 , they can scale well beyond 1 mm in diameter while remaining single crystalline 13,26 . Exhibiting strong optical cavity effects, these structures are natural nanoresonators 27 .…”

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confidence: 99%

Nanophotonic integrated circuits from nanoresonators grown on silicon

Chen

et al. 2014

Nat Commun

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Harnessing light with photonic circuits promises to catalyse powerful new technologies much like electronic circuits have in the past. Analogous to Moore's law, complexity and functionality of photonic integrated circuits depend on device size and performance scale. Semiconductor nanostructures offer an attractive approach to miniaturize photonics. However, shrinking photonics has come at great cost to performance, and assembling such devices into functional photonic circuits has remained an unfulfilled feat. Here we demonstrate an on-chip optical link constructed from InGaAs nanoresonators grown directly on a silicon substrate. Using nanoresonators, we show a complete toolkit of circuit elements including light emitters, photodetectors and a photovoltaic power supply. Devices operate with gigahertz bandwidths while consuming subpicojoule energy per bit, vastly eclipsing performance of prior nanostructure-based optoelectronics. Additionally, electrically driven stimulated emission from an as-grown nanostructure is presented for the first time. These results reveal a roadmap towards future ultradense nanophotonic integrated circuits.

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Atomically sharp catalyst-free wurtzite GaAs∕AlGaAs nanoneedles grown on silicon

Cited by 111 publications

References 21 publications

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

Single Crystalline InGaAs Nanopillar Grown on Polysilicon with Dimensions beyond the Substrate Grain Size Limit

Nanophotonic integrated circuits from nanoresonators grown on silicon

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