Growth and characterization of site-controlled InAs(Sb) nanowires for use in infrared photodetectors

Alhodaib, Aiyeshah (2017) Growth and characterization of site-controlled InAs(Sb) nanowires for use in infrared photodetectors. PhD thesis, UNSPECIFIED.

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There is considerable interest in the development of InAs(Sb) nanowires for infrared photonics due to their high tunability across the infrared spectral range and integration with silicon electronics applications. The use of nanowires in IR photonics also promises transformational advantages. Site-controlled catalyst free epitaxial growth on silicon wafers was used in this work to enable exploitation of recent scientific understanding in the control of light matter interactions through geometry, while also offering practical integration advantages and strong, tuneable optical emission. However, optical emission is currently limited to low temperatures due to strong non-radiative Auger and surface recombination. Simple structures suffer from deleterious effects due to the high surface to volume ratio in nanowires which has limited emission to fixed wavelengths and low temperatures, until now. In this thesis the growth of InAs(Sb) has been developed to realize high performance costeffective optoelectronic structures for the development of emitters and photodetectors operating in the mid-infrared spectral range. In addition to characterizing the optical properties of the grown nanowires, this research has improved their optical efficiency by reducing nonradiative surface and Auger recombination. The growth of advanced InAs nanowires containing embedded multiple quantum well (MQWs) and superlattices (SL) structures is reported for the first time. The MQWs and SL structures are based on type II InAsSb/InAs MQWs which exhibit bright mid-infrared photoluminescence up to room temperature. This unique geometry confines the electron-hole recombination to within the quantum wells which alleviates the problems associated with recombination via surface states, whilst the quantum confinement of carriers increases the radiative recombination rate and suppresses Auger recombination. This demonstration paves the way for the development of new integrated quantum nano-light sources operating in the technologically important mid-infrared spectral range. In this work we also realized the first InAsSb shortwave infrared nanowire photodetectors and the lowest leakage current density reported for any InAs(Sb) photodiode at 300 K. Using the same method of growth (site-controlled epitaxy), allowed for high quality shortwave nanowire infrared photodetectors to be grown on silicon substrates, while obtaining surprisingly low leakage current density. The unique design of these nanowire photodetectors also allows for electrical conduction through the substrate which simplifies many aspects of the fabrication and expands the opportunities for integration. Although the nanowires occupy only a small fraction of the light collection area, optimization of the length and diameter can significantly increase the absorbance up to that of planar films. Combined with the reduction in leakage current density over InAs(Sb), this should provide more than 2 orders of magnitude increase in signal-noise ratio over state-of-the-art InAs(Sb) devices. This represents a major step toward high-performance mid-infrared photodetectors compatible with silicon technologies and which can potentially be integrated with other photonic systems.

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Thesis (PhD)
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30 Jan 2018 11:22
Last Modified:
17 Sep 2023 03:32