GaN based Static Induction Transistor (GaN-SIT) for high power application
Abstract
Vertical GaN devices are ideal for high power applications owing to their widebandgap-originated material properties, similar to SiC. What makes GaN vertical devicesmore attractive than SiC, is the capability to offer bulk regions with an electron mobilityover 1200cm2/V??sec and channels regions, often higher than 2000cm2/V??sec withappropriate use of polarization engineering. In spite of our recent advancements, the majortechnological challenges for vertical GaN devices have not yet been adequately addressed,and represent hurdles that cannot be overstated. The lack of a robust buried p-n junction inGaN has, to-date, limited the possibilities of device classes that are typical in Si and SiCtechnologies. Mg is a deep acceptor in GaN offering less than 1% activation under roomtemperature. The percentage of active Mg in the crystal reduces with increasing bandgapmaking it increasingly difficult to realize robust p-n junction performing as designed, underthe switching operation of the devices. The other challenge in GaN is the realization of apristine oxide-semiconductor interface for maintaining high channel mobility. The channelmobility in an Al2O3-GaN interface cannot improve beyond ~ 300cm2/V??s. Lower channelmobility implies a higher Ron besides oxide-GaN interface introducing trapping and poorthreshold voltage control under switching operation. All variants of vertical GaNMOSFETs and CAVETs suffer from both of these issues, and therefore while tacklingthese issues, we will focus on static induction transistors (SIT). For its functioning, a SITDOES NOT rely on the p-type doping, polarization doping, or the gate oxide dielectriclayer for active transport. A successful SIT performance ensures high-voltage switching athigher frequencies (up to 500MHz); broadening the window of possibilities for reliableapplications.SiC SITs have shown the potential for high power and high frequency applications.With higher electron mobility and higher saturation velocity than SiC, GaN SITs have thepotential to operate at higher frequency with higher output power.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2018
- Source ID
- N000141812677
Entities
People
- Srabanti Chowdhury
Organizations
- Office of Naval Research
- United States Navy
- University of California, Davis