Near-constant thermoelectric power factor of GaN two-dimensional hole gas in cryogenic environments
Lex Pardon (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Diana C. Leitao (Eindhoven University of Technology)
Filipe A. Cardoso (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Karen M. Dowling (TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
This work investigates the thermoelectric properties of a gallium nitride (GaN)-based two-dimensional hole gas (2DHG) using a double heterojunction, which can be utilized in complementary GaN thermoelectric (TE) platforms for power generation in extreme environments. A 5 × 1012cm−2 hole density, a Hall mobility of up to 20 cm2 V−1s−1, and a Seebeck coefficient of 0.4 mV K−1 have been measured, resulting in a power factor of 0.5-1.0 mW m−1K−2 over a 300–77 K temperature range. These results demonstrate the stability and usability of the thermoelectric properties of GaN using hole conduction at sub-100 K temperatures, therefore providing clear evidence that GaN-based 2DHGs can function as a stable cryogenic TE platform, opening new opportunities for complementary device architectures (leveraging both 2DHGs for p-type and two-dimensional electron gases for n-type) optimized for extreme environment electronics commonly encountered in deep-space missions, where other materials become unreliable.
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