Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

Abstract

The influence of electric field (EF) on the dynamic ON-resistance (dyn-RDS[ON]) and threshold-voltage shift (ΔVth) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (IDS-VDS) and drain current (ID) transients. Different EF was realized with devices of different gate-drain spacing (Lgd) under the same OFF-state stress. Under high-EF (Lgd = 2 μm), the devices exhibited higher dyn-RDS[ON] degradation but a small ΔVth (∼120 mV). However, at low-EF (Lgd = 5 μm), smaller dyn-RDS[ON] degradation but a larger ΔVth (∼380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-RDS[ON] degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔVth. A trap with activation energy 0.33 eV was identified in the AlGaN barrier by ID-transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations.

Trap behaviours characterization of AlGaN/GaN high electron mobility transistors by room-temperature transient capacitance measurement

“…Electrical stress applied to the device could induce both temporary and permanent current collapse because of electron traps in AlGaN/GaN HEMTs. 24 The drain stress induced trap density changing is studied based on the above-presented transient capacitance measurement. A step-stress (see Fig.7) is applied to the drain electrode with a negative bias of -15 V on the gate (device is at off-state).…”

Quantitative characteristics of traps in AlGaN/GaN MIS-HEMT via transient capacitance measurement

“…The gate-drain distance (L GD ) is 10µm and the gate-source (L GS ) is 2µm. Applied electrical stress to the device could induce both temporary and permanent current collapse because of electron trapping in AlGaN/GaN HEMTs [13]. In this study, a negative bias of -15V (V G ) was applied to the gate electrode, and V D increased from 5V to 25V with a step of 5V to study the effect of electric stress induced trap in AlGaN/GaN MIS-HEMT.…”

Investigation of interface properties of h-BN and AlN on AlGaN/GaN heterostructures

“…C/O/H Impurities 0.44,0.45 0.58 [137], [139] VGa+Oxygen complex 0.58, 0.65 [137] Nitrogen Interstitials 0.73 [137] Fe dopant 0.57, 0.72 [140], [141] Nitrogen vacancies 0.27 [142] Possible AlGaN surface 0.34 [143] Gallium vacancies 0.8 [144] GaN native defects 0.62, 0.65 [139], [145] Nitrogen Anti-sites 0.51, 0.55, 0.69 [146] conditions. Some examples include defect, dislocations, or impurities in the crystal structure as seen in table 2.1.…”