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

Investigation of ON-State Breakdown Mechanism in AlGaN/GaN HEMTs with AlGaN Back Barrier

“…The impact-ionization-induced detrapping behavior was also confirmed by the appearance of bell-shaped features in the gate leakage current at V DS > 6 V, as the device is turned ON during transfer characterizations (Figure 1b). The impact ionization would induce electron-hole pairs with holes captured by the gate electrodes [22,23]. Meanwhile, the impact-ionization-induced detrapping behavior also causes a negative shift of V TH , as shown in Figure 1b.…”

“…At I G of −1 µA/mm, the monitored V DS increased rapidly with I D in the OFF-state as V GS was below V TH . The gate leakage current in this region was expected to be dominated by electrons injected from the gate into the channel through thermionic field emission and tunneling, and the increase of the V GS was driven by the increase of the drain current to turn on the channel gradually [23]. Once V GS increased above V TH and turned the device ON, lower drain bias voltage was enough to sustain the drain current, until an upsurge of I D featuring infinite conductance was observed.…”

“…The abrupt increase of I D in the ON-state breakdown locus of I G = −1 µA/mm (Figure 2a) implies that impact ionization takes place near the drain-side gate edge in AlGaN/GaN HEMTs [16,[18][19][20][21][22][23][24]. A large amount of holes can thus be generated in this high-field region, and some of them are collected by the gate electrode, contributing a new leakage current component I hole , which makes a dominant contribution to I G in the infinite conductance region (I D versus V DS ) [16].…”

“…This was due to the reduction of the peak electric field in the gate-drain region (roughly proportional to V DG ) and consequently of the impact ionization rate, as V GS increased further with I D . To maintain a constant I G , a higher V DS was required again [23]. Moreover, the forward bending of BV ON loci became more evident at a higher temperature, since the impact ionization features a negative temperature coefficient.…”

Off‐state and on‐state breakdown of GaAs MESFET, PHEMT and Power PHEMT

“…3 The devices on-state breakdown loci 3.1 Correlation between on-state breakdown loci and I GS -V GS characteristics Figure 3 (b) presents the on-state breakdown loci of the PPHEMT, the PHEMT and the MESFET for an identical gate current condition: I GS =-1 mA/mm and measured using the gate-current extraction technique [5]. Three zones can be distinguished on the on-state breakdown loci depending on the conduction regime of the device [6,7]. Let us consider the BV-on state locus of a PHEMT in Fig.…”