Surface passivation effects on AlGaN/GaN high-electron-mobility transistors with SiO2, Si3N4, and silicon oxynitride
Влияние пассивации поверхности на транзисторы с высокой подвижностью электронов AlGaN/GaN с использованием SiO2, Si3N4 и оксинитрида кремния
2004-01-25
SCID: 54.1/djqbn235
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AlGaN/GaN HEMTsbreakdown voltagesilicon oxynitride (SiON)surface passivationsurface-related traps
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Abstract (AI)
Surface passivation effects were studied on AlGaN/GaN high-electron-mobility transistors (HEMTs) using SiO2, Si3N4, and silicon oxynitride (SiON) formed by plasma enhanced chemical vapor deposition. An increase of IDmax and gmmax has been observed on the passivated (SiO2, Si3N4 and SiON) HEMTs when compared with the unpassivated HEMTs. About an order of magnitude low IgLeak and three orders of magnitude high IgLeak was observed on Si3N4 and SiO2 passivated HEMTs, respectively, when compared with the unpassivated HEMTs. The increase of IgLeak is due to the occurrence of surface related traps, which was confirmed by the observation of kink and hysteresis effect on dc and ac IDS–VDS characteristics, respectively. Though the Si3N4 passivated HEMTs show better dc characteristics, the breakdown voltage (BVgd) characteristics are not comparable with SiO2, SiON passivated and unpassivated HEMTs. The SiON is also a very promising candidate as a surface passivant for AlGaN/GaN HEMTs because it shows better BVgd with low hysteresis width and small ID collapse than Si3N4 passivated HEMTs.
Key Findings
1
Although Si3N4-passivated HEMTs exhibited better DC characteristics, their gate-drain breakdown voltage was inferior to that of SiO2-passivated, SiON-passivated, and unpassivated HEMTs.
2
Si3N4 passivation reduced gate leakage current by about one order of magnitude, whereas SiO2 passivation increased it by three orders of magnitude relative to unpassivated devices.
3
SiO2, Si3N4, and SiON passivation increased the maximum drain current (IDmax) and transconductance (gmmax) compared with unpassivated AlGaN/GaN HEMTs.
4
SiON emerged as a promising passivation material, combining better gate-drain breakdown voltage with low hysteresis width and small drain-current collapse compared with Si3N4.
5
The increased leakage in SiO2-passivated HEMTs was attributed to surface-related traps, evidenced by kink and hysteresis effects in DC and AC IDS–VDS characteristics.
Research Object
AlGaN/GaN high-electron-mobility transistors (HEMTs) with SiO2, Si3N4, and SiON surface passivation
Research Subject
The effects of dielectric surface passivation on HEMT electrical performance, including drain current, transconductance, gate leakage, surface-trap-induced hysteresis and kink effects, breakdown voltage, and current collapse
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2004-01-25
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