Keeping the heat out

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Most electronic devices currently contain silicon-based chips. Other semiconducting materials show potential, but need further research to become commercially viable. Researchers at KAUST have thoroughly analyzed one such material—metal-nitride nanowires—bringing them a step closer to being useful.

When metal-nitride semiconductors are arranged into nano-sized wires, they become extra sensitive to light, opening possibilities for optical electronics. One notable challenge however is that although metal-nitride nanowires perform well at low temperatures, thermal effects can greatly affect their performance at room temperature. To address this problem, Nasir Alfaraj with his PhD supervisor Xiaohang Li and coworkers at KAUST have produced the most detailed study yet of these thermal effects.

The researchers prepared gallium-nitride (GaN)-based nanowires in a p-i-n structure—a sandwich with layers of so-called p-type and n-type versions of the semiconductor surrounding an unaltered layer. N-type semiconductors are doped with materials that provide extra electrons, while p-types are doped with materials with fewer electrons, leaving “holes” in the crystal structure. Both electrons and holes act as charge carriers, giving semiconductor devices their useful electronic properties.

“GaN-based p-i-n nanowires are suitable for fabricating signal attenuators, high-frequency digital switches and high-performance photodetectors,” said Alfaraj. “Yet, their performance is negatively affected when electrons and holes recombine, especially close to room temperature.”

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