High Power, Broadband, Linear, Solid State Amplifier.
Abstract
Undoped polarization induced-electron HEMT's have been grown and processed on sapphire and SiC substrates. Devices with gate lengths between .15 and 75 pm have been fabricated. With .15 pm gates, fL = 75 GHz and drain-source breakdown voltage of 35 V have been achieved. These values were 20 GHz and 140 V for .75 pm gates. Electron mobility values of 1,505 cm2/V-s on SiC (oMVPE) and 1,232 cm2IV-s on sapphire (MBE) have been obtained with 2 DEG density of'l.3-l.5 x lO'3/cm2 . Optimum devices in 3 GHz operation yielded >70% power-added efficiency. The SIT device etching problem is solved using a combination of dry (ECR) and wet (hot KOH) etching. A traveling wave monolithic circuit will be used for our non-uniformly distributed power amplifier with no backward wave. Large periphery (.5-1 mm) transistor tells" are being tested, and for this circuit. Modeling of devices, Monte Carlo simulation of electron transport in short devices, and fundamental physics of GaN are all being undertaken, as is simulation of electron tunneling in from the Schottky gate. High resistivity V-doped SiC is supplied by Northrop Grumman, and bulk GaN growth is being developed. Using RHEED to obtain the correct (Ga) ice, MBE growths of HEMT's is successful. An eight-wafer OMVPE reactor is operational, and refinements to yield increased uniformity and low output conductance are being developed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1998
- Accession Number
- ADA354429
Entities
People
- B. Fontz
- B. Green
- K. Chu
- Lester F. Eastman
- N. Weimann
Organizations
- Cornell University College of Engineering