Excimer laser liftoff of AlGaN/GaN HEMTs on thick AlN heat spreaders
Abstract
We report on 193 nm excimer laser-based liftoff (LLO) of Al0.26Ga0.74N/GaN high electron mobility transistors (HEMTs) with thick (t > 10 μm) AlN heat spreading buffer layers grown over sapphire substrates. The use of the thick AlN heat spreading layer resulted in thermal resistance (Rth) of 16 K mm/W for as-fabricated devices on sapphire, which is lower than the value of ∼25–50 K mm/W for standard HEMT structures on sapphire without the heat-spreaders. Soldering the LLO devices onto a copper heat sink led to a further reduction of Rth to 8 K mm/W, a value comparable to published measurements on bulk SiC substrates. The reduction in Rth by LLO and bonding to copper led to significantly reduced self-heating and drain current droop. A drain current density as high as 0.9 A/mm was observed despite a marginal reduction of the carrier mobility (∼1800 to ∼1500 cm2/V s). This is the highest drain current density and mobility reported to-date for LLO AlGaN/GaN HEMTs.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 27, 2021
- Source ID
- 10.1063/5.0064716
Entities
People
- Abdullah Mamun
- Asif Khan
- Grigory Simin
- Kamal Hussain
- M. V. S. Chandrashekhar
- Md. Didarul Alam
- Mikhail Gaevski
- Mohi Uddin Jewel
- Richard Floyd
- Shahab Mollah
Organizations
- Army Research Office
- Division of Electrical, Communications & Cyber Systems
- University of South Carolina