Understanding hot-electron transport in silicon devices: Is there a shortcut?

Abstract

Results of a Monte Carlo study of carrier multiplication in silicon bipolar and field-effect transistors and of electron injection into silicon dioxide are presented. Qualitative and, in most cases, quantitative agreement is obtained only by accounting for the correct band structure, all relevant scattering processes (phonons, Coulomb, impact ionization), and the highly nonlocal properties of electron transport in small silicon devices. In addition, it is shown that quantization effects in inversion layers cause a shift of the threshold energy for impact ionization which is very significant for the calculation of the substrate current in field-effect transistors. Conservation of parallel momentum, image-force corrections, dynamic screening of the interparticle Coulomb interaction, and improvements to the WKB approximation are necessary to treat correctly the injection of electrons from silicon into silicon dioxide. The validity of models-analytic or Monte Carlo-which treat hot-electron transport with oversimplified physical approximations is argued against. In a few words, there is no shortcut. 0 I995 Ametican Institute of Physics.

Time-resolved optical characterization of electrical activity in integrated circuits

“…Mean free paths in Si are typically a few hundred angstroms. An electron in the conduction channel of a silicon nFET subject to an electric field of about V/cm can acquire about 1 eV of kinetic energy over the distance of a mean free path [23]. One result of this heating is that states of the conduction band that are unoccupied in the absence of an applied field can become occupied.…”

“…Significant near-infrared and visible light emission, which involve carriers with more than 1 eV of kinetic energy, is only generated in the pinch-off region of the FET in saturation. The calculations of Fischetti et al [23] determine the energy distribution of carriers in the channel even if the distribution is nonthermal. For electric fields below V/cm, electrons are generally characterized by a Maxwell-Boltzmann like distribution for higher kinetic energies.…”

“…Fischetti et al [23] calculated the energy distribution of electrons in a saturated, deep submicrometer Si nFET (0.15-m effective channel length, 0.25-m metallurgical channel length, V and V). The calculated dependence of the average electron energy on the position in the channel is shown in Fig.…”

Numerical Simulation of Electric Characteristics of Deep Submicron Silicon-on-Insulator Mos Transistor

“…Impact ionization is a threshold process [24][25][26]. In a simple case, threshold energy E th can be determined using the energy and momentum conservation laws and minimization of the energy of final particles.…”

Source-Side Injection Modeling by Means of the Spherical-Harmonics Expansion of the BTE

“…A hydrodynamic simulation is carried out to evaluate the energy barrier profile and the current loss factor due to electron scattering in the oxide [5], as well as the potential distribution, which is required as an input for HARM.…”