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

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.

Inspec keywords: power HEMT; electric fields; gallium compounds; piezoelectricity; power semiconductor switches; nitrogen compounds; III-V semiconductors; oxidation; failure analysis; silicon compounds; electrostatic discharge; passivation

Other keywords: gallium nitride-based transistors; MIS-HEMT structures; electric field; time-dependent degradation; dynamic effects; passivation robustness; electrostatic discharge event; switching frequency; failure modes; threshold voltage instabilities; deep-level effects; trapping-de-trapping equilibrium condition; silicon nitride; enhancement gallium nitride HEMT; surface oxidation; power switching applications; charge trapping; depletion reliability; depletion-mode high electron mobility transistors; gate injection transistors; inverse piezoelectric effect; power dissipation; gate dielectric; enhancement-mode high electron mobility transistors; off-state stress

Subjects: Surface treatment (semiconductor technology); Piezoelectric and ferroelectric materials; Reliability; Other field effect devices; Power semiconductor devices; Electrostatics; Relays and switches

http://iet.metastore.ingenta.com/content/journals/10.1049/iet-pel.2017.0403
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