Temperature dependence of the impact ionization coefficients in GaAs, cubic SiC, and zinc-blende GaN

Abstract

In this article we discuss the effect of temperature on the impact ionization coefficients in wide band-gap semiconductors and compare it to that of bulk GaAs. The impact ionization coefficients as a function of temperature are examined for three semiconductors: gallium arsenide, cubic phase silicon carbide, and zinc-blende phase gallium nitride. It is found that the magnitude of the phonon energy is principally responsible for changes in the impact ionization coefficients as a result of temperature change. While the energy band gap of a material does have a temperature dependence that directly affects the impact ionization transition rate, that change is much smaller than the relative change in the magnitude of the phonon-scattering rates in all of the materials studied here. The phonon energies are found to play a vital role in the magnitude of the change in the scattering rates as a function of temperature. Materials with relatively small phonon energies have phonon scattering rates that change considerably with temperature, and therefore have impact ionization coefficients that also change considerably with changes in temperature. Conversely, the phonon scattering rate in materials with a large phonon energy is less affected and thus these materials have impact ionization coefficients that are relatively insensitive to changes in the temperature.

Temperature Dependence of Electron and Hole Impact Ionization Coefficients in GaN

“…As can be seen, very good agreement is obtained. In addition, we observe that the temperature dependence obtained in [20], the longitudinal optical (LO) phonon energy of GaN (∼92 meV) is appreciably larger than that of many other semiconductors, leading to reduced temperature dependence of the avalanche coefficients.…”

“…3 shows the extracted hole impact ionization coefficients at 298, 348, and 398 K as a function of the inverse electric field. The hole impact ionization coefficients decrease with temperature due to the increased phonon scattering rate at elevated temperatures [20]. The data were fitted using the following equations based on the Okuto-Crowell model [21]: where E is the electric field (V/cm) and T is the temperature in Kelvin (T 0 = 298 K).…”

Temperature dependence of avalanche multiplication and breakdown voltage in Al0.52In0.48P

“…Through Full Band Monte Carlo simulations of impact ionization process for binary semiconductors such as GaAs, cubic SiC, and zincblende GaN, Tirino et al showed that large phonon energy reduced the change in phonon scattering rates with temperature and therefore should lead to weak temperature dependence of impact ionization coefficients in those semiconductors. 26 Similarly, Xiao and Deen speculated that large phonon energy will lead to a small C bd . 27 However, further investigation by Groves et al showed no clear correlation between phonon energy and C bd (Ref.…”

TCAD Device Modelling and Simulation of Wide Bandgap Power Semiconductors

“…b The formed energy level is considered from the valence band (E V ). Notably, it has been found in [26] that these values are relatively insensitive to temperature variations in the range of 300 K < T < 500 K. For 4H-SiC, a slightly different model is utilized after Hatakeyama's work [27] to effectively describe the anisotropic behaviour of the avalanche coefficients. The avalanche force is considered to have two components to account for the anisotropic structure of 4H-SiC [28], satisfying…”