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Thermoelectric properties of group-IV SiGeSn alloys and thermoelectric conversion devices


Key facts

Type of research degree
Application deadline
Ongoing deadline
Country eligibility
International (open to all nationalities, including the UK)
Dr Zoran Ikonic
Additional supervisors
Professor Robert Kelsall, Dr Dragan Indjin
School of Electronic and Electrical Engineering
<h2 class="heading hide-accessible">Summary</h2>

Energy harvesting for Internet of Things applications requires efficient thermoelectric (TE) materials, which should ideally be semiconductors compatible with Si technology. While pure Si or Ge are not good candidates for these applications, mostly because of their large lattice thermal conductivity, the GeSn and SiGeSn alloys are much more promising options, both because of the small lattice thermal conductivity and because of large electron mobility in cases where the band gap is direct. This thesis will perform the theoretical / modelling investigation of the potential of GeSn and SiGeSn alloys as TE materials for low-grade heat to electricity conversion. The previously calculated expected TE figures of merit of ZT &sim; 0.4 at 300 K and an impressive 1.04 at 600 K. These values are extremely promising in view of the use of GeSn/Ge layers operating in the typical on-chip temperature range.<br /> <br /> The modelling will be based on k.p and effective mass method for the band structure parameters in the conduction and valence band, followed by calculations of carriers mobility, Seebeck coefficients, and thermal conductivity due to various scattering processes (acoustic, optical, and intervalley phonon scattering, alloy disorder, ionised impurity, and lattice defects induced scattering). Based on these calculations the promising alloy compositions will be identified, to deliver a large power factor and / or large ZT parameter, which describe the power output or the conversion efficiency of bulk material based thermoelectric generators. <br /> <br /> Further work will then be directed towards more complex structures which can improve the TE generators performance. Instead of homogeneous-composition bulk alloys, the modulated-composition structures will be explored, where the composition modulation leads to the modulation of the conduction and valence band edges, which enables energy filtering in carrier transport, eventually leading to improved heat-to-electricity conversion. Optimal design of devices with energy filtering effect will then be investigated. <br />

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="">University&#39;s website</a>. Please state clearly in the Planned Course of Study Section that you are applying for <em><strong>PHD Electronic &amp; Electrical Engineering FT</strong></em> and in the research information section&nbsp;that the research degree you wish to be considered for is <em><strong>Thermoelectric properties of group-IV SiGeSn alloys and thermoelectric conversion devices</strong></em> as well as&nbsp;<a href="">Dr Zoran Ikonic</a> as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p style="margin-bottom:11px"><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p> <p class="MsoNoSpacing">Applications will be considered on an ongoing basis. &nbsp;Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application. &nbsp;We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p>Please note that you must provide the following documents at the point you submit your application:</p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> <li>Funding information including any alternative sources of funding that you are applying for or if you are able to pay your own fees and maintenance</li> </ul> <p>&nbsp;</p>

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<h2 class="heading">Funding on offer</h2>

<p style="margin-bottom:12px"><strong>Self-Funded or externally sponsored students are welcome to apply.</strong></p> <p><strong>UK&nbsp;</strong>&ndash;&nbsp;The&nbsp;<a href="">Leeds Doctoral Scholarships</a> and <a href="">Leeds Opportunity Research Scholarship</a> are available to UK applicants (open from October 2023). <a href="">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Non-UK </strong>&ndash;The&nbsp;<a href="">China Scholarship Council - University of Leeds Scholarship</a>&nbsp;is available to nationals of China (open from October 2023). The&nbsp;<a href="">Leeds Marshall Scholarship</a>&nbsp;is available to support US citizens. <a href="">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Important:</strong>&nbsp; Any costs associated with your arrival at the University of Leeds to start your PhD including flights, immigration health surcharge/medical insurance and Visa costs are <strong>not </strong>covered under these studentships.</p> <p>Please refer to the <a href="">UKCISA</a> website for information regarding Fee Status for Non-UK Nationals.</p>

<h2 class="heading">Contact details</h2>

<p>For further information regarding your application, please contact Doctoral College Admissions<br /> e:&nbsp;<a href=""></a></p> <p>For further information about this project, please contact Dr Zoran Ikonic<br /> e:&nbsp;<a href=""></a></p>