Electronics for Venus exploration: gallium nitride semiconductors tested at 500℃

Gallium nitride is advertised as the next-generation semiconductor that may one day replace silicon, but research on this material is still in its early stages. Researchers from Massachusetts Institute of Technology and other US institutions have decided to take the technology to the next level and tested the material at temperatures above 500℃.

Human desire to explore the planets of the Solar System covers not only those far from the Sun. Extreme temperatures on Venus instantly melt lead, regular electronics won't survive even for a moment there.

Even if researchers sent a spacecraft with a heat-resistant exterior, the onboard silicon-based electronics would weaken under extreme temperatures, rendering the exercise futile.

Gallium nitride can withstand temperatures above 500℃, but scientists actually had little knowledge of how electronics developed using this material would operate above 300℃, the operating limit of devices made from silicon. To study the impact of temperature on ohmic contacts, researchers placed contacts under a temperature of 500℃ for 48 hours straight. They found that the contacts remained structurally intact, which is a promising sign for the development of high-performance transistors.

Despite gallium nitride being advertised as the next-generation semiconductor, it will take years of study for scientists to achieve its widespread use. For example, researchers have very little information about its stability. The resistance of gallium nitride is inversely proportional to its size. Although this can be circumvented, semiconductors also need to be connected to other electronics, providing their resistance. This resistance, called contact resistance, remains fixed in the device, and an excess of it makes the devices inefficient.

To better understand contact resistance in gallium nitride devices, researchers from MIT created structures consisting of a series of resistors to measure contact resistance and material resistance. In collaboration with Rice University, researchers placed these structures on hot stages at a temperature of 500℃ and measured their resistance. The structures were kept inside a special oven for 72 hours to determine how resistance changes over time. Contact resistance remains unchanged even at high temperatures, however, after 48 hours the material began to degrade. The research results were published in the journal Applied Physics Letters.