Novel Short-Wave Mid-Infrared Devices for Si Photonics Applications

This proposed project is to be a continuation of the work undertaken for the past two years under the
supervision of Professor Stephen Sweeney, who is transferring to the University of Glasgow in October 2022.
Work completed during this time frame has focused primarily on light emitting devices that are epitaxially
grown on Si platforms. This area is of particular interest for the realisation of optoelectronic integrated circuits
(OEICs) for Si photonics applications, as many of the passive components have already been successfully
developed. Whilst III-Vs have illustrated success when integrated via wafer bonding techniques, epitaxial
growth of high-quality active regions remains ideal for scaling manufacturing processes.

This broad topic is subdivided into two related but distinct areas of interest. Firstly, in laser devices
on Si operating in the 2-3um range. Due to the abundance of molecular absorption lines in this spectral
region, realising high-quality emitters at these wavelengths promises the development of lab-on-a-chip OEICs
for applications in medical and environmental sensing. By utilising high hydrostatic pressure- and temperature dependent
measurement techniques, in conjunction with band modelling, we are able to investigate efficiency
limiting mechanisms resulting from carrier dynamics [1, 2]. Thus far, this has been achieved for GaSb and GeSn
investigate as part of an ongoing collaboration with the universities of Montpellier and Arkansas, respectively,
with papers in the pipeline for both. This is an activity that will continue for a number of novel samples over
the duration of the project.

The second aspect of the project focuses on quantum dot based single photon sources on silicon. This has
been based on a collaboration with UCL. From the start of the third year, attention will be placed primarily
on the development of novel long wavelength quantum-dot based single-photon emitters on Si. Semiconductor
quantum dots are a leading candidate for on-demand single-photon sources for quantum information processing
applications. This work is complementary to research at the university (e.g. the group of Dr Luca Sapienza).
Whilst most devices are typically based on InAs technologies operating in the near infrared around 900nm, it
would be preferable to push this emission toward the telecommunications O- and C-bands at 1300 and 1550nm,
respectively. This would enable transmission off-chip through standard fibre optics with minimised losses. Such
a reduction in emission energy can be achieved through bandgap engineering by alloying III-Vs with Bi, as
proposed by the Sweeney group at Surrey [3]. In this work we propose doping of low density InAs quantum dot
samples with a low-density flux of Bi ions in an attempt to shift emission into the mid-infrared, with an aim of
moving towards near-deterministic implantation of pre-selected dots. Characterisation is to then be conducted
utilising a combination

References
[1] B. N. Murdin, A. R. Adams, and S. J. Sweeney. Band structure and high-pressure measurements. In Anthony
Krier, editor, Mid-infrared Semiconductor Optoelectronics, pages 93-127. Springer London, London, 2006.
[2] S. J. Sweeney, T. D. Eales, and I. P. Marko. The physics of mid-infrared semiconductor materials and
heterostructures. In Eric Tourni'e and Laurent Cerutti, editors, Mid-infrared Optoelectronics, Woodhead
Publishing Series in Electronic and Optical Materials, pages 3-56. Woodhead Publishing, 2020.
[3] I. P. Marko and S. J. Sweeney. The physics of bismide-based lasers. In ShuminWang and Pengfei Lu, editors,
Bismuth-Containing Alloys and Nanostructures, pages 263-298. Springer Singapore, Singapore, 2019.