Astro-technology seminar
Time: Monday, October 8, 2018, at 15:30
Location: FCUL, building C1, room 1.4.14
Speaker:
Elliot R. Brown (Wright State University)
Abstract:
InP-based resonant-tunneling-diode (RTD) oscillators have advanced beyond the 1.0 THz barrier and are currently enabling new THz systems applications, especially in wireless communications and radar. In this presentation, we will address our recent seminal report of a new RTD-type optical emitter from the hexagonal GaN/AlN materials system. Because of the huge intrinsic polarization fields at the GaN-AlN interfaces, these RTDs are more challenging than their cubic GaAs and InP counterparts. This required a complete redesign through rigorous modeling to overcome asymmetries, as well as process and growth challenges. Over the past 3 years, we realized the first reported stable, room-temperature NDR in GaN/AlN RTDs, with very high peak current densities (>> 2×10^5 A/cm^2), enabling up to >>100 GHz oscillation and ps switching in the wide bandgap material system for the first time. In addition, we discovered that GaN/AlN RTDs emit strong near-UV radiation at the GaN bandgap, which has been explained by resonant-, interband- “co-tunneling”, and establishes for the first time a semiconductor-based photonic technology which requires no p-type doping. The universal nature of this new mechanism has recently been established through near-IR light measurements made on more traditional In0.53Ga0.47As/AlAs-on-InP RTDs. The potential for high-efficiency LEDs and high-speed laser diodes will also be addressed.