Researchers from JNCASR, the University of Sydney and IISc have created a crystal that delivers nearly 1,000 times the thermoelectric voltage of the textbook limit. They used magnesium-doped scandium nitride (ScN) thin films to make a heavily doped, highly compensated semiconductor, challenging the accepted limit of the Seebeck effect, which turns a temperature difference into voltage. X-ray diffraction and atomic-resolution electron microscopy confirmed the films are single-crystalline and epitaxial. The material could enable ultrasensitive temperature sensors, heat detectors and quantum sensing devices.