We report Monte Carlo particle (MCP) simulations of the current response and noise spectrum in heavily doped nanometric GaAs Schottky-barrier diodes (SBDs) operating under static, cyclostationary and resonant-circuit conditions in the forward bias region. Main attention is paid to the SBDs application in the THz frequency region. General features of the regular response and noise as well as their modifications under various operation modes are obtained from MCP simulations and analyzed in the framework of a simple analytical model based on the static I-V and C-V relations obtained from simulations.
The investigation of noise in electronic devices operating under large-signal conditions is attracting increasing attention in recent years. Theoretical analyses on this subject are typically performed in the framework of the impedance field method, implemented under the drift-diffusion approximation. As an alternative, a more general microscopic approach including a more detailed physical description of the systems is mandatory. This work reviews recent results of Monte Carlo simulations of electronic noise in bulk materials and submicron semiconductor structures subject to high-frequency large-amplitude periodic electric fields or applied voltages/currents.
The peculiarity of the noise analysis under large-signal operation is that velocity or current/voltage fluctuations appear simultaneously with the regular response of the nonlinear medium or device, so that the regular response and noise spectra are overlapped in the whole frequency range of interest. Here, various correlation functions of fluctuations, their instantaneous and integrated spectral densities, etc. are calculated under large-signal operation for compound semiconductors, such as GaAs, and InN, as well as for GaAs Schottky-barrrier diodes and n+nn+ structures. A comparison with the results obtained under stationary conditions is performed. Under these large-signal cyclostationary working conditions, when the system response becomes nonlinear, several modifications and anomalies appear in the noise spectra with respect to static stationary conditions. In particular, an increase of the low-frequency noise and a resonant-like enhancement of the spectra near the fundamental frequency (and eventually high-order harmonics) of the applied signal is observed under some specific conditions. These anomalies are interpreted as a manifestation of dynamical effects under sufficiently high frequency and amplitude of the applied signal. Similarities and differences of the noise resonant-like enhancement around the fundamental frequency with noise upconversion processes are discussed.