Abstract-Probing the photophysics of semiconductor nanomaterials using optical pump-terahertz probe spectroscopy: from nanowires to perovskites

Hannah J. Joyce, Lissa Eyre, Stephanie O. Adeyemo, Sarwat A. Baig, Jessica L. Boland, Christopher L. Davies, Michael B. Johnston, Felix Deschler, H. Hoe Tan, C. Jagadish,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10724/107240F/Probing-the-photophysics-of-semiconductor-nanomaterials-using-optical-pump-terahertz/10.1117/12.2320720.short?SSO=1

Optical pump-terahertz probe spectroscopy is a powerful contact-free technique for probing the electronic properties of novel nanomaterials and their response to photoexcitation. This technique can measure charge carrier transport and dynamics with sub-picosecond temporal resolution. Electrical conductivity, charge carrier lifetimes, mobilities, dopant concentrations and surface recombination velocities can be measured with high accuracy and with considerably higher throughput than achievable with traditional contact-based techniques. We describe how terahertz spectroscopy is revealing the fascinating properties and guiding the development of a number of promising semiconductor materials, with particular emphasis on III-V semiconductor nanowires and devices.

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Abstract-Engineering semiconductor nanowires for photodetection: from visible to terahertz

Hannah J. Joyce,  Jack Alexander-Webber, Kun Peng,  Michael B. Johnston, Patrick Parkinson,  H. Hoe Tan, C. Jagadish

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10729/1072909/Engineering-semiconductor-nanowires-for-photodetection-from-visible-to-terahertz/10.1117/12.2320715.short

III–V semiconductor nanowires combine the properties of III–V materials with the unique advantages of the nanowire geometry, allowing efficient room temperature photodetection across a wide range of photon energies, from a few eV down to meV. For example, due to their nanoscale size, these show great promise as sub-wavelength terahertz (THz) detectors for near-field imaging or detecting elements within a highly integrated on-chip THz spectrometer. We discuss recent advances in engineering a number of sensitive photonic devices based on III–V nanowires, including InAs nanowires with tunable photoresponse, THz polarisers and THz detectors.

Abstract-Investigations of doping via optical pump terahertz-probe spectroscopy

 Jessica L. Boland,   A. Casadei,   G. Tütüncouglu,  F. Matteini , C. Davies,  F. Gaveen, F. Amaduzzi,   H.J. Joyce,  L.M. Herz,   A. Fontcuberta i Morral,  Michael B. Johnston

http://ieeexplore.ieee.org/document/8066895/

Reliable doping in semiconductor nanowires is essential for the development of novel optoelectronic devices. Dopant incorporation within the nanowire can allow for optimisation of key optoelectronic properties, such as electron mobility and carrier lifetime. Thus, in-depth characterisation of doping mechanisms in semiconductor nanowires and their effect on the nanowire optoelectronics properties is crucial. However, extraction of the dopant concentration by conventional electrical methods remains difficult due to the associated challenges with fabricating lateral contacts onto the nanowire. In this work, we present a non-contact technique based on optical pump terahertz-probe spectroscopy for examining the extrinsic carrier concentration and optoelectronic properties of semiconductor nanowires. By extracting the temperature-dependent charge carrier dynamics, we show for the first time that the dopant activation energy and underlying scattering mechanisms affecting charge carrier mobility in these nanostructures can be determined via terahertz spectroscopy.