Ultra-low defect-density GaN HEMTs with Superjunction-Drain for enhanced radiation tolerance
Abstract
Executive SummaryMotivation: Prior studies show the fluence of ionizing radiation at which GaN devices such asHEMTs and LEDs start degrading is about at least two orders of magnitude higher than in theirGaAs equivalents. This difference is attributed to the stronger bonding of GaN. The highdisplacement energy for GaN relative to Si and GaAs translates to more resistance to creation ofpoint defects during irradiation. The displacement energy varies inversely as the volume of the unitcell for many semiconductors [Pearton-Polyakov]. For these fundamental reasons, and the factthat GaN is one of the most versatile semiconductors of our time, with its imprint on automotive,wireless, and industrial power applications, but not quite as much into space and avionicapplications, we propose GaN based low voltage (LV) HEMTs to fulfill the DARPA SPCE metricsunder TA2.Approach and Novelties: However standard HEMTs are not enough for the radiation-hardeningsolutions and realize the full potential of GaN in space applications. The two strategies that willfeature our proposed (LV) HEMT are 1) superjunction-drain added to HEMTs (SJN-HEMT) tolower the peak electric field and enhance the volts-per-micron and ii) superlattice channels addedto SJN-HEMT to increase the maximum current by taking advantage of the peak electric fieldlowering (due to SJN) (see Figure 1). Superlattice FETs (SLCFETs), alone, and in combinationwith diamond SJN, has been studied to an extent, but not extensively for radiation hardness[Chang-Howell, Afroz-Hobart]. The novelty we bring to the table is in our SJN implementation,where we will grow high quality, large grain p-type diamond in one of the embodiments. The ptypediamond SJN layer also will act as a heat spreader that will allow enhancing the device#slifetime by reducing the peak temperature. In another embodiment we will modify the SJN drainwith p-type GaN.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 24, 2023
- Source ID
- N000142312756
Entities
People
- Srabanti Chowdhury
Organizations
- Office of Naval Research
- Stanford University
- United States Navy