Methodology to compare on-state breakdown loci of GaAs FET's

On-state breakdown loci of three technologies (power PHEMT, PHEMT and MESFET) have been measured using gate-current extraction techniques. We present a precise understanding of the correlation between the on-state breakdown voltage (BV on-state) locus and the reverse Igs-Vgs characteristics. From the comparison of Igs-Vgs characteristics, this study has allowed establishing a methodology to compare BV-on state of the devices under test. We have found that for technologies with impact ionization occurring at pinch off, such as the PHEMT technology with a high leakage gate current, the on-state breakdown locus presents a pronounced "exponential" shape. On the contrary, a technology with high impact ionization component in the gate current, such as the PPHEMT technology, presents a shape of the on-state breakdown locus rather "hyperbolic". We assess that technologies with impact ionization occurring at pinch off such as the PHEMT and PPHEMT present a more "hyperbolic" shape of the on-state breakdown locus than technologies with impact ionization occurring in open channel regime such as the MESFET.