Wide bandgap group III-nitride (III-N) based semiconductor devices, especially the lateral power devices based on the AlGaN/GaN-on-silicon power platform, are emerging as highly attractive candidates for the next generation high-efficiency power electronics system, owing to their high breakdown voltage, low ON-resistance, fast switching speed and high operation temperature. The near-term approach to implementing GaN-based power electronics system relies on multi-chip solutions involving separate discrete GaN power chips and silicon driver chips. To further improve performance, obtain better reliability and possibly lower cost, it is desirable to explore single-chip solutions for the ultimate system-on-chip (SOC) implementation.

In the first part of this thesis, we focus on the developm...[ Read more ]

Wide bandgap group III-nitride (III-N) based semiconductor devices, especially the lateral power devices based on the AlGaN/GaN-on-silicon power platform, are emerging as highly attractive candidates for the next generation high-efficiency power electronics system, owing to their high breakdown voltage, low ON-resistance, fast switching speed and high operation temperature. The near-term approach to implementing GaN-based power electronics system relies on multi-chip solutions involving separate discrete GaN power chips and silicon driver chips. To further improve performance, obtain better reliability and possibly lower cost, it is desirable to explore single-chip solutions for the ultimate system-on-chip (SOC) implementation.

In the first part of this thesis, we focus on the development of technology platform for implementing single-chip integration of III-N power devices with peripheral devices following two directions: 1) Heterogeneous integration of III-N and Si devices; and 2) All-GaN solution with all the functional blocks realized with GaN-based devices.

The heterogeneous integration of GaN electronic devices and Si devices (e.g. MOSFETs) could take advantage of the mature high-integration-density Si MOSFET technology and many existing design techniques. The major challenge for such a heterogeneous integration is the different Si crystal orientations required for III-N epitaxial gtowth and Si-CMOS technology. High-quality GaN epi-growth requires (111) Si while the mainstream CMOS technologies have been developed on (100) Si substrates. A GaN-on-SOI technology is developed in this work. The modified SOI wafer with a (111) Si device layer and a (100) Si handling wafer naturally provides two different Si orientations for implementations of GaN and Si devices. High-voltage (1.4 kV) depletion-mode (D-mode) and enhancement-mode (E-mode) AlGaN/GaN HEMTs are demonstrated on the GaN-on-SOI platform. Micro-Raman spectroscopy reveals stress-free GaN epilayers which is attributed to the compliant nature of SOI substrate. With monolithically integrated enhancement/depletion (E/D)-mode AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs), a high-voltage low-standby power start-up circuit for powering up the future GaN-based off-line switch mode power supply (SMPS) during the start-up period is demonstrated.

The second part of this thesis focuses on the substrate crosstalk between the high-voltage power devices and low-voltage circuits in GaN-on-Si technology. This crosstalk is investigated by monitoring the dc I-V or transient characteristics of a GaN HEMT with a high-voltage switched bias applied to an adjacent isolated electrode under two different substrate terminations, i.e. floating and grounded. It is found that the substrate-assisted coupling results in conduction current degradation of the lateral device when the substrate is floating. When the substrate is grounded, the crosstalk can be effectively suppressed. The underlying mechanisms of the substrate termination's influence on devices' stability are revealed.