Differentiated Doping Profile for Vertical Terahertz GaN Transferred-Electron Devices

The potential of vertical differentiated gallium nitride (GaN) transferred electron devices (TEDs) is compared with that of the base flat doping profile TED for the realization of RF power sources at 1 THz. The TED oscillator modeling is a time-domain continuous wave pure sine model. The semiconductor device model is a 1-D numerical physical macroscopic model based on the energy-momentum approach. Differentiated structures of notch, detached notch, and P⁺ spike (PS) types have been optimized. By contrast with millimeter-wave differentiated TEDs operating in the dipole domain mode, the terahertz TED RF operating mode remains the accumulation layer/transit time mode. Comparison point out that the differentiated doping profile TEDs slightly improve both the TED RF performance and electronic limitation but above all improve the thermal limitation resulting from the high dc bias conditions due to high threshold electric field in GaN. Thus, the PS TED distinguishes itself as the most promising structure.