Review of dynamic effects and reliability of depletion and enhancement GaN HEMTs for power switching applications

Abstract

GaN-based transistors are promising devices for power switching applications, but their unique properties require careful design of the circuit in order to achieve the best performance and reliability. The first part will focus on the characterisation of deep-level effects in enhancement-and depletion-mode HEMTs, which limit the performance of the transistor. Threshold voltage instabilities in MIS-HEMT structures, caused by charge trapping under the gate, and their dependence on SiN acting as the gate dielectric will be reviewed. ON-resistance increase, caused by charge trapping in the gate-drain access region, will then be discussed in normally off gate injection transistors, as well as the effect of the switching frequency on the trapping-de-trapping equilibrium condition. The second part of the paper will discuss possible failure modes related to operating conditions, starting with the oxidation of the surface and the inverse piezoelectric effect at high gate-drain voltage. To have a complete picture of high-field effects, the gate dielectric and passivation robustness will be investigated. Time-dependent degradation will then be analysed in both gate reverse and forward-bias conditions. Finally, failures related to off-state stress and to power dissipation and electric field during an ESD event in AlGaN/GaN-HEMTs will be discussed.

Analysis of Trap and Recovery Characteristics Based on Low-Frequency Noise for E-Mode GaN HEMTs Under Electrostatic Discharge Stress

“…Moreover, the large two-dimensional (2-D) electron gas concentration confined by a larger conduction band discontinuity between GaN and AlGaN and the presence of polarization fields enhances the carrier mobility (1500-2000 cm -2 /V) in AlGaN/GaN material system [1]. As a result, the high two-dimensional electron gas (2DEG) density (10 13 cm -2 ), high electron peak velocity (3×10 7 cm/s) and high electron saturation velocity (1.5×10 7 cm/s) constitute important advantages of AlGaN/GaN hetero-junction with respect to their silicon (Si) and GaAs counterpart [2][3][4]. GaN-based high-electron mobility transistors (HEMTs) are emerging as a key technology for high frequency, high power, and high temperature applications [5][6][7][8][9].…”

Use of Bilayer Gate Insulator in GaN-on-Si Vertical Trench MOSFETs: Impact on Performance and Reliability

“…Vertical GaN technologies [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] are gaining popularity for power conversion applications [ 8 , 11 ], owing to the superior power handling capabilities compared to the lateral configuration [ 12 , 13 , 14 ], combined with the inherent material advantages of GaN. Among various vertical architectures, trench MOSFETs on Si substrates [ 3 , 4 , 8 , 10 ] have substantial economic advantages, in addition to promising performance metrics.…”

A Parametric Technique for Trap Characterization in AlGaN/GaN HEMTs

“…However, a recent wide agreement is that the transient current degradation involves both device charge trapping and self-heating [11]- [14] at different times. Therefore, the time constants of the transient current need to be investigated since they are of critical consequence to device reliability and RF performance [17]. Consequently, the charge trapping is essential effect entering a design space of circuits [15] because a circuit dynamic operation affects a device operation as accounted for in an MIT virtual source GaN HEMT model [16].…”