Impact of traps in N-polar GaN HEMTs on performance and reliability
Abstract
A 36-month basic research program is proposed to investigate traps in N-polar GaN high electron mobility transistors (HEMTs), identify the physical sources of the traps, identify the accelerators that cause trap activation/formation that lead to degradation. These things will delay insertion into DoD platforms and need to be resolved quickly. Traps are known to cause many problems in N-polar GaN HEMTs including threshold voltage instability, knee walkout, current collapse, and reduced transconductance, for example. N-polar HEMTs have many potentialadvantages over more developed Ga-polar devices due to the opposite polarization that enables different device structures that enable lower contact resistance, better two-dimensional electron gas confinement, more effectively highly-scale geometries, higher operating frequencies, and higher power densities. To create ideal devices that do not have any time- and bias-dependentinstabilities and that do not suffer from any trap-related degradation, the inherent traps and stress induced traps need to be characterized using our suite of defect spectroscopy measurements in conjunction with RF and DC accelerate life testing. We plan to build on our success in multiple ONR-supported efforts where some of our most notable successes are (a) the development of alibrary of GaN traps and their potential physical sources, (b) directly relating the EC-0.57 eV GaN buffer trap to HEMT output power degradation and showed this was not simply due to the application of RF stressing or elevated temperature, (c) relating the effects of traps in Ga-polar GaN HEMTs on nonlinearity, and (d) developing several new defect spectroscopy techniques including scanning-deep level transient spectroscopy (DLTS) and constant drain current DLTS(CID-DLTS). In the proposed work, we will build from the knowledge attained in our previous programs and expand into several new directions inspired by those results, with the ultimate goal to enable highly reliable, state-of-the-art N-polar GaN HEMTs. These areas of focus are: (a) baselining current generation N-polar GaN HEMTs, (b) investigate the dielectric/N-polar GaN interfaces to determine the impact of this interface, (c) study the impact of electric field and/or hot carriers on trap modulation for improved device modeling, (d) investigate RF and DC accelerated life testing and ensuing trap evolution to determine the limiting factors of reliability, (e) identify the impact of traps on linearity in N-polar devices. The expected outcome is specific knowledge to improve N-polar GaN HEMTs related to the many effects traps can have on devices and systems.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 17, 2020
- Source ID
- N000142012663
Entities
People
- Aaron R. Arehart
Organizations
- Office of Naval Research
- Ohio State University
- United States Navy