PIB TrackerA crystalline solid breaks the textbook ceiling on thermopower
Scandium nitride films doped to a heavily compensated state show a Seebeck coefficient beyond -124.6 millivolts per Kelvin, a range previously seen only in liquid electrolytes.
What happened
- A team from JNCASR, an autonomous institute of DST, with the University of Sydney and IISc, broke the accepted ceiling on the Seebeck effect in a solid.
- They grew epitaxial scandium nitride (ScN) films on magnesium oxide by ultrahigh-vacuum magnetron sputtering, doping with magnesium to compensate oxygen-donated electrons.
- In a film about 200 nanometres thick the Seebeck coefficient exceeded -124.6 millivolts per Kelvin near room temperature — a liquid electrolyte range.
- A prototype photon sensor with two chromium contacts gave a response of -102.4 millivolts per Kelvin, fast and repeatable over multiple cycles.
- The findings are published in Science and an Indian patent application has been filed on the thin-film materials and sensors.
For Prelims
- Seebeck effect: a voltage generated across a junction of dissimilar materials when one end is heated and the other kept cold; discovered about two centuries ago.
- Seebeck coefficient: the measure of that voltage per degree; metals give tens of microvolts per Kelvin, semiconductors rarely a few hundred.
- The previous ceiling: only liquid systems — ionic gels, electrolytes, hydrogels — had reached millivolts per Kelvin, with ions rather than electrons carrying the heat.
- The result: a Seebeck coefficient exceeding -124.6 mV/K near room temperature, nearly a hundred times beyond the earlier known ceiling for solids.
- HDHC: a heavily doped, highly compensated semiconductor, with positive and negative dopants scattered randomly in nearly equal numbers.
- ScN: scandium nitride, a refractory transition-metal nitride, grown epitaxially on magnesium oxide and doped with magnesium.
- Institutions: JNCASR (autonomous under DST), the University of Sydney and IISc Bengaluru; the team was led by Prof. Bivas Saha.
- Applications named: ultrasensitive temperature sensing, low-noise thermal imaging, bolometric devices, IoT sensors and cryogenic thermoelectric single-photon detectors.
For UPSC: A rare instance of frontier Indian materials physics with a named journal, a named limit overturned and a patent filed. Use it on research and development capability, on quantum and sensing technologies, and on the translation of basic science into instruments.
What it is NOT: This is not a breakthrough in generating power from waste heat — the demonstrated device is a sensor, and a large Seebeck coefficient alone does not make an efficient thermoelectric generator.
For Mains
Syllabus: GS3.11 · GS3.13 · Linkage L1
Anchor
The team was not hunting a record; they were asking how disorder reshapes transport in scandium nitride, and the textbook limit fell out of a question about defects.
Substantiation (data)
A Seebeck coefficient beyond -124.6 millivolts per Kelvin near room temperature in a film of about 200 nanometres — hundreds to over a thousand times typical inorganic semiconductor values and nearly a hundred times the earlier ceiling — with a prototype photon sensor at -102.4 millivolts per Kelvin.
Exemplification
The prototype is two chromium contacts on a film: illuminate one, create a local temperature difference, read a voltage — a photon detector built out of a thermal effect.
Problematisation
A result at the 200-nanometre film scale, strengthening as films thin, is a long way from a manufacturable device, and the release offers no figure for efficiency, yield or stability outside the laboratory.
Way-forward
The stated route is cryogenic single-photon detection for quantum technologies, where a very large voltage per Kelvin matters more than conversion efficiency; the patent application is on sensors, not generators.
Position
Engineered disorder — deliberately spoiling a crystal with equal numbers of opposite dopants — is being treated here as a design parameter rather than a defect, which is the more portable finding of the two.
Deploys into: Science and technology in everyday life + research and IPR (GS3.11, GS3.13) · sensing technologies, and basic research translating into patented instruments.
Ministry of Science & Technology · 2026-08-31 · PRID 2305021 · PIB source ↗