A study of on-state and off-state breakdown voltages in GaN MESFETs

We present the experimental results on the three-terminal on-state and off-state breakdown voltage studies of recessed-gate GaN MESFETs. Typical values of BV_DG=57 V and BV_DS= 46 V for the off-state breakdown voltages (BV) were measured at a value of current I _G=-0.05 mA/mm. On-state BV measurements were carried out at constant extracted gate current values of I_G=-0.01 mA/mm and -0.05 mA/mm with the drain current being swept from I_D=|I_G| (off-state) to I_D=5 mA/mm (on-state). The values for BV_on loci at I_D=|I_G| (off-state) match the results for the off-state BV measurements. In addition, a collapse of the I-V curves characterized by suppressed drain currents was observed after each BV experimental run, but the original I-V curves could be recovered after exposure to light from a blue LED. We relate the collapse of the drain current to the presence of electron traps