Reliability of H-terminated diamond MESFETs in high power dissipation operating condition

The aim of this work is to study the catastrophic and gradual degradation of H-terminated diamond MESFETs. Such devices are able to withstand high power densities before failure, but are still affected by a bias-dependent degradation. The main degradation modes are both an increase in ON-resistance and threshold voltage. The effect of this device degradation seems to be caused by the higher concentration of a 0.3 eV deep level. Moreover, the presence of a possible variation in hole transfer efficiency cannot be excluded, especially at the highest stress biases. Electroluminescence measurements confirm the increase in hole scattering, and highlight a progressive reduction in peak electric field in the device under test, possibly due to a virtual field plate effect.