Nitride GEN II
The plasma nitride system is a Varian Gen II horizontal reactor with 8 source ports plus a pyrometry port. As of 12/12/2008, the available source materials are Ga, Al, In, Si (n-dopant), a dual dopant cell/gas injector for Mg(p-dopant)/CBr4(for semi-insulating buffers), and two RF-plasma nitrogen sources. Unlike most other compound semiconductors, a metal-rich surface is necessary for the the MBE-growth of group-III nitrides to achieve smooth surface morphology and low impurity incorporation under typical growth conditions below the decomposition limit of GaN. We recently acquired a nitrogen source which offers very high growth rates (a few microns/h) and hence enables much higher growth temperatures without the need to maintain a metal adlayer. A quadruple mass spectrometer can be installed into one of the source ports for in-situ monitoring of growth dynamics.
This system has been the primary tool for the rich research of MBE-grown III-N materials and devices at UCSB. AlGaN/GaN high electron mobility transistors (HEMTs) with outstanding high frequency performance have been fabricated on materials grown in this system. Recent activities on this system include:
- N-rich/high-temperature GaN growth for low defect density materials
- N-polar GaN HEMTs for next generation mm-wave and digital switching devices
- GaN on silicon substrates
- Solar cells
- Polarization-doped tunnel junctions for LED devices
- Devices on non-polar nitride epilayers
The following are links to important papers based on the work on the system:
Richard Cramer's paper on BGaN
Brian McSkimming's paper on High N-Flux Growth on GaN
Erin Kyle's paper on InAlN Growth
