Nitrides Seminar - Ashley Wissel-Garcia

Attend in person at ESB 1001!
Zoom option also available

Meeting ID: 867 5890 7577           

Passcode: 206296

Ashley Wissel-Garcia
Graduate Student Researcher, Speck Group
University of California, Santa Barbara

NH3-MBE Growth of AlN and AlGaN
for Next-Generation RF Devices

The pursuit of higher operating frequencies for radio frequency (RF) electronics creates new demand for materials that can withstand larger electric fields while maintaining high conductivity. High Al-content AlGaN has a theoretical high critical electric field and saturation velocity which make it an ideal candidate for these applications. AlGaN has long been used in high electron mobility transistors and in electron blocking layers in III-Nitride light emitting diodes (LEDs). When growing these alloys, careful consideration must be given to the choice of substrate, as the large in-plane lattice mismatch between c-plane GaN and AlN can lead to morphological breakdown if stresses become too large. For this reason, high Al-content AlGaN is best grown on AlN substrates or buffer layers to ensure the stresses in the material are compressive, rather than tensile, to avoid cracking. Achieving high quality AlN buffer layers is essential to producing the next generation of AlGaN RF devices and UV-LEDs due to the challenge of removing impurities from the substrate-regrowth interface and the importance of insulating buffers to mitigate leakage. This talk will present recent progress in the growth of AlN and high-Al-content AlGaN by ammonia molecular beam epitaxy (NH3-MBE) at UCSB, including the development of an AlN growth regime diagram, control over structural quality and relevant impurities in AlGaN, as well as the application of these materials in RF devices.

HOST: Dr. Yifan Yan