Atomic Resolution Structure and Spectroscopy of Semiconducting Nanowires

Lead Research Organisation: University of Warwick
Department Name: Physics

Abstract

Condensed matter: electronic structure
The field of semiconductor nanowires (NWs) has become one of the most active research areas in the nanoscience community in the last five years. Integration of semiconducting NWs with the well-established capabilities and low production cost of silicon is crucial for the implementation of novel quantum emitters, such as single photon sources on Si.
Development of this area requires control of the nanowire structure with atomic precision, and this in turn is reliant on the ability to map structural and electronic properties with atomic resolution. With the recent advances in hardware, such as aberration correction, electron microscopy is the technique of choice to disentangle the structural properties of the material and correlate them with the functional ones.
This project will involve the atomic scale characterisation of a range of semiconducting nanowires, supplied by our collaborators who are internationally leading nanowire growth experts. The successful applicant will be trained in the use of the doubly aberration corrected TEM/STEM at Warwick, the only such facility in the UK, which has the capability for sub-Å resolution imaging and spectroscopy. The aim will be to determine the atomic scale structure and composition of the nanowires, and to correlate these to changes in optical properties and electronic structure. Calculation of the critical dimensions for the plastic relaxation of axial heterostructures in nanowires is also anticipated. The candidate will be joining a group with an internationally-competitive electron microscopy facility with excellent specimen preparation and microscopy and many years of experience studying semiconductor materials. Strong collaboration with external partners at Universities (such as UCL, Sheffield and Lancaster universities) and semiconductor industries will be an essential part of the project.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509796/1 01/10/2016 30/09/2021
1764986 Studentship EP/N509796/1 03/10/2016 30/06/2020 James Adam Gott
 
Description Nanowires are a class of material that have a diameter of a few nms and are a few microns in length. This material system has a reputation of being mostly free of structural imperfections. This work has been able to show that depending on how they are grown, it is possible for these materials to have a wide range of different types of structural defects. Some of the defect structures found are not found in other material systems. If these defects are present in a nanowire, they can be detrimental to electronic and optical properties. A number of these defects are not observable using more conventional techniques and requires high magnification imaging in a scanning transmission electron microscope. It has been shown that using an appropriately high enough temperature, heating nanowires with defects encourages a number of the defects to move, and can be completely removed from the nanowire. This shows a simple annealing process after the material is grown could be an easy way improve the material quality.
Exploitation Route The information can be used by people who grow nanowire structures to improve material quality.
Sectors Electronics,Energy,Manufacturing, including Industrial Biotechology,Other