Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High Electron Mobility Transistors

Li, Yat; Xiang, Jie; Qian, Fang; Gradečak, Silvija; Wu, Yue; Yan, Hao; Blom, Douglas A.; Lieber, Charles M.

doi:10.1021/nl060849z

Cited by 359 publications

(282 citation statements)

References 38 publications

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“…In this figure, the y-axis is linear with (W) 2 , so that the obtained linear characteristics demonstrate that the abrupt junction theory is appropriate. Similar donor and acceptor doping levels are inferred in the axial and radial junctions.…”

Section: −3mentioning

confidence: 69%

Direct Imaging of p–n Junction in Core–Shell GaN Wires

et al. 2014

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While core−shell wire-based devices offer a promising path toward improved optoelectronic applications, their development is hampered by the present uncertainty about essential semiconductor properties along the threedimensional (3D) buried p−n junction. Thanks to a crosssectional approach, scanning electron beam probing techniques were employed here to obtain a nanoscale spatially resolved analysis of GaN core−shell wire p−n junctions grown by catalyst-free metal−organic vapor phase epitaxy on GaN and Si substrates. Both electron beam induced current (EBIC) and secondary electron voltage constrast (VC) were demonstrated to delineate the radial and axial junction existing in the 3D structure. The Mg dopant activation process in p-GaN shell was dynamically controlled by the ebeam exposure conditions and visualized thanks to EBIC mapping. EBIC measurements were shown to yield local minority carrier/exciton diffusion lengths on the p-side (∼57 nm) and the n-side (∼15 nm) as well as depletion width in the range 40−50 nm. Under reverse bias conditions, VC imaging provided electrostatic potential maps in the vicinity of the 3D junction from which acceptor N a and donor N d doping levels were locally determined to be N a = 3 × 10 18 cm −3 and N d = 3.5 × 10 18 cm −3 in both the axial and the radial junction. Results from EBIC and VC are in good agreement. This nanoscale approach provides essential guidance to the further development of core−shell wire devices.

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Section: −3mentioning

confidence: 69%

Direct Imaging of p–n Junction in Core–Shell GaN Wires

et al. 2014

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“…Metal-organic chemical vapour deposition (MOCVD) 51 has been extensively applied for growth of compound semiconductor NWs. [54][55][56] Silicon core/multi-shell NWs with high-quality electronic interfaces…”

Section: Synthesis Of Nanowiresmentioning

confidence: 99%

Semiconductor nanowires: a platform for exploring limits and concepts for nano-enabled solar cells

Kempa

Day

Kim

et al. 2013

Energy Environ. Sci.

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Abstract:Over the past decade extensive studies of single semiconductor nanowire and nanowire array photovoltaic devices have explored the potential of these materials as platforms for a new generation of efficient and cost-effective solar cells. This feature review discusses strategies for implementation of semiconductor nanowires in solar energy applications, including advances in complex nanowire synthesis and characterization, fundamental insights from characterization of devices, utilization and control of the unique optical properties of nanowires, and new strategies for assembly and scaling of nanowires into diverse arrays that serve as a new paradigm for advanced solar cells. 2 Table of Contents Entry:Advanced synthetic control over the electronic and optical properties of semiconductor nanowires enables testing new paradigms for advanced solar cells. Broader Context Box:The solar power received by the earth dwarfs global power demands by several orders-ofmagnitude. Photovoltaics convert light to electrical energy and have the potential to partially replace current energy technologies that rely on carbon-based fuels. At present, however, a lack of infrastructure and the high costs of photovoltaics prevent this. New ideas and materials are being explored to develop next-generation solar cells that could operate more efficiently and cheaply. Nanowires have emerged as one promising platform to explore such new concepts.Their small dimensions allow for efficient charge separation and light absorption properties unique as compared to bulk materials. Furthermore, the synthesis and fabrication of nanowire devices differs significantly from traditional wafer-based technologies, thus presenting new opportunities such as use of less abundant materials or cheaper substrates. Here, we discuss the benefits and remaining challenges of nanowires for PV and review progress towards understanding and optimizing the electrical and optical performance of nanowire devices. We focus on single nanowire studies that can define limits for what is achievable when multiple nanowires are assembled. Challenges and initial progress towards scaling are presented, and, for the first time, we articulate unique capabilities of solar cells derived from multiple, distinct NWs. 6

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“…12 Radial nanowire heterostructures consist of core and shell ͑or multishell͒ morphologies, which offer flexibility to engineer the band gaps of a radial nanowire heterostructure and thereby, desired properties can be obtained. 13,14 Many potential applications have been demonstrated using these radial nanowire heterostructures including multicolor light-emitting diodes, 14 address decoders, 15 high electron mobility transistors, 16 and nonvolatile crossbar switches. 17 Exploration of the fundamental mechanism͑s͒ of radial growth is essential to produce the practically useful radial nanowire heterostructures with desired composition, structure, and morphology.…”

mentioning

confidence: 99%