Modulation doping of GaAs/AlGaAs core-shell nanowires with effective defect passivation and high electron mobility.

Abstract

Reliable doping is required to realize many devices based on semiconductor nanowires. Group III-V nanowires show great promise as elements of high-speed optoelectronic devices, but for such applications it is important that the electron mobility is not compromised by the inclusion of dopants. Here we show that GaAs nanowires can be n-type doped with negligible loss of electron mobility. Molecular beam epitaxy was used to fabricate modulation-doped GaAs nanowires with Al0.33Ga0.67As shells that contained a layer of Si dopants. We identify the presence of the doped layer from a high-angle annular dark field scanning electron microscopy cross-section image. The doping density, carrier mobility, and charge carrier lifetimes of these n-type nanowires and nominally undoped reference samples were determined using the noncontact method of optical pump terahertz probe spectroscopy. An n-type extrinsic carrier concentration of 1.10 ± 0.06 × 10(16) cm(-3) was extracted, demonstrating the effectiveness of modulation doping in GaAs nanowires. The room-temperature electron mobility was also found to be high at 2200 ± 300 cm(2) V(-1) s(-1) and importantly minimal degradation was observed compared with undoped reference nanowires at similar electron densities. In addition, modulation doping significantly enhanced the room-temperature photoconductivity and photoluminescence lifetimes to 3.9 ± 0.3 and 2.4 ± 0.1 ns respectively, revealing that modulation doping can passivate interfacial trap states.

DOI: 10.1021/nl504566t

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Cite this paper

@article{Boland2015ModulationDO, title={Modulation doping of GaAs/AlGaAs core-shell nanowires with effective defect passivation and high electron mobility.}, author={Jessica L Boland and Sonia Conesa-Boj and Patrick Parkinson and G{\"{o}zde T{\"{u}t{\"{u}nc{\"{u}oğlu and Federico Matteini and Daniel R{\"{u}ffer and Alberto Casadei and Francesca Amaduzzi and Fauzia Jabeen and Christopher L Davies and Hannah J Joyce and Laura M Herz and Anna Fontcuberta I Morral and Michael B Johnston}, journal={Nano letters}, year={2015}, volume={15 2}, pages={1336-42} }