Monte Carlo Analysis of DC–AC Conversion Efficiency in Highly Doped Planar GaN Gunn Diodes: Effects of Applied Bias, Doping Level, and Temperature

This study investigates the performance of planar Gunn diodes based on highly doped gallium nitride (GaN) using Monte Carlo simulations. The conversion efficiency is evaluated in geometrically V-shaped channels with an active region length of 500 nm, an input channel width of 200 nm, and output widths of 200, 220, and 250 nm. The diodes are subjected to various biasing conditions to assess dc-to-ac conversion efficiency under different ac biases, simulating operating conditions similar to those found in tuned circuits (comprising R, L, and C elements). The efficiency is analyzed for an ac voltage of 2 V superimposed on a 20-V dc bias, considering four distinct doping levels in the active region. These devices demonstrate conversion efficiencies of up to 0.36% at frequencies of 340 GHz for a channel doping level of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${N}_{\text {D}} = 1.0\times {10}^{{18}}$ </tex-math></inline-formula> cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{3}}$ </tex-math></inline-formula> and an output width of 250 nm. The increase in lattice temperature reduces the efficiency of the diodes, although the obtained values indicate that the devices would still remain operational. In addition, the frequency range where efficiency is positive (generation band) decreases as temperature increases.