Trap assisted avalanche instability and safe operating area concerns in AlGaN/GaN HEMTs

On the trap assisted stress induced safe operating area limits of AlGaN/GaN HEMTs

“…Figure 5(a) shows the variation in trap density in various regions of the device. A significant increase in trap density is noticed in the gate-drain region [9] with increasing drain stress. Here gate-to-drain trap density increases at a much higher rate than in the gate-tosource region.…”

“…MOCVD grown AlGaN/GaN stack, possess a finite defect density which can introduce non-uniformity in carrier trapping and associated peak field shift, at drain, along the device width. Enhanced impact ionization and carrier injection into the buffer, in these localized high field regions invokes avalanche instability and causes multiple damages [9] as seen in Fig. 8(b).…”

“…The outstanding properties of Gallium Nitride (GaN) such as wide bandgap (3.4 eV), high breakdown field (3.3 MV/cm), good thermal conductivity (1.3 W/cm 2 -K) and low dielectric constant (9) have triggered the replacement of Si by GaN in power device applications. GaN based high electron mobility transistor (HEMT) have shown outstanding performance in high power and high frequency domain [1].…”

“…Long term reliability of these devices has been studied in greater details in the recent literature [1]- [7]. However, a clear understanding of the physical phenomena active under high electric field and high current injection conditions, which define the safe operating area (SOA) limit in GaN HEMT, is still missing in the literature [8], [9]. Therefore, a study to gain insight into possible degradation mechanisms which limit the SOA reliability in GaN HEMT is a worthwhile effort.…”

Recent progress of physical failure analysis of GaN HEMTs

“…In 2016, Shankar et al [23] reported three failure mechanisms of GaN HEMTs under ESD stress conditions: (a) Devices without mesa isolations and gate contacts fail owing to the migrations of metal contacts from the drain to the source. Metal migrations at the contact corners are remarkable, due to the existence of the largest field crowding there.…”