GaN/AlGaN Based Complementary p~+- p~--p-n~+ ATT-Device for Application in THz Imaging

摘要

A detailed simulation investigation is carried out on the hetero-structure complimentary (p~+p-p-n~+) IMPATT oscillator for Terahertz power generation. It is observed that this newly proposed GaN/AlGaN IMPATT may generate a pulsed power density of ~8xl0~(10) Wm~(-2) with an efficiency of 11%, whereas it's flatly doped counterpart is capable of delivering a pulsed power density of only 3x10~(10) Wm~(-2) with 7% efficiency. The total parasitic series resistance, Rs, including that due to the un-depleted region in device and also the effects of ohmic contact resistances, has been found to be a major problem that reduces the negative resistance significantly and thus it has a detrimental effect on THz oscillation of the device. The study reveals that the value of Rs decreases by 40% as the structure, semiconductor material pair as well as doping profile of the diode changes suitably from conventional to the proposed hetero-structure p~+-p -p-n+ type , by incorporating a 300A~0 Al_(0.4)Ga_(0.6)N layer in the p-drift region. This first study will be a useful guide in the THz-sector to meet the ever-increasing demand of semiconductor THz-sources for application in Imaging or in improvised explosive device (IED) detection.