Leakage current and capacitance characteristics of Si/SiO2/Si single-barrier varactor

We investigate, both experimentally and theoretically, current and capacitance (I-V/C-V) characteristics and the device performance of Si/SiO2/Si single-barrier varactor diodes (SBVs). Two diodes were fabricated with different SiO2 layer thicknesses using the state-of-the-art wafer bonding technique. The devices have very low leakage currents (about 5 x 10(-2) and 1.8 x 10(-2) mA/mm(2)) and intrinsic capacitance levels of typically 1.5 and 50 nF/mm(2) for diodes with 5-nm and 20-nm oxide layers, respectively With the present device physical parameters (25-mm(2) device area, 760-mum modulation layer thickness and approximate to 10(15)-cm(-3) doping level), the estimated cut-off frequency is about 5 x 10(7) Hz. With the physical parameters of the present existing III-V triplers, the cut-off frequency of our Si-based SBV can be as high as 0.5 THz.