Project Objective

Electrical characterization and thermal stability of Gallium Nitride (GaN) power devices at ultra-low temperature conditions.

Project Description

Power devices are microelectronic areas quickly evolving to allow for fast communications, wide band-gap and high-frequency sensing features. Applications in deep space and on lunar/martial surfaces demand reliability under harsh environmental conditions and extreme thermal cycles, with requirements of material compatibility and stability at low temperature. Surface temperatures on Mars and on the Moon are close to -150C and -170C, respectively, and electronics are expected to withstand thermal cycles of -120 to 120C with some level of thermal packaging protection. Will perform verification and material screening as well as functional performance of GaN devices to ensure success of insertion of new technologies and new materials in the areas of microelectronics for fast communication, wide band-gap and high frequency electronic devices.

Project Results and Conclusions

GaN power devices were characterized non-destructively and destructively before and after thermal shock. Testing suggests that GaN metal-oxide-semiconductor field effect transistors (MOSFETs) are reliable and can operate within specification after extreme temperature exposure. Performance reliability was determined by comparing threshold voltage (Vth) values before and after thermal shock to the gate-to-source threshold voltage found within the manufacturer’s part datasheet. Additionally, radiography evaluations support the electrical functionality testing; radiographs show minimal change to the porosity and part architecture following the shock. The packaging of GaN devices was investigated via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

Thermal shock testing entailed transferring the devices from a 150°C furnace to liquid nitrogen (-196°C). Device operation was screened before and after thermal shock with basic electrical functionality screening. Each device was tested three times before and after shock, nonconsecutively. The device was characterized via Id-Vgs and Id-Vds curves. The threshold voltage (Vth) was calculated by extrapolating a square root plot of the Id to zero drain current. Each device’s threshold voltages remained in specification before and after the thermal shock, suggesting that the tested GaN devices can operate reliably following extreme temperature cycling.

•Enhance functionality in deep space comm and sensing electronics, with selection, and thermal material characterization of waveguide transistors, diodes, supercapacitors, layered electronics, optoelectronic, and photonic discrete devices as examples.

•Fast screening of commercial off-the-shelf (COTS) discrete parts or packing devices/materials before integration on sensing communication, power systems or circuits boards.

•Failure analysis of electronic and packaging materials and thermal characterization of electronics materials.