Hole transport properties of bulk zinc-blende and wurtzite phases of GaN based on an ensemble Monte Carlo calculation including a full zone band structure

Abstract

In this paper, we present calculations of the hole transport properties of bulk zinc-blende and wurtzite phase GaN at field strengths at which impact ionization does not occur significantly. The calculations are made using an ensemble Monte Carlo simulator, including the full details of the band structure and a numerically determined phonon scattering rate based on an empirical pseudopotential method. Band intersection points—including band crossings and band mixings—are treated by carefully evaluating the overlap integral between the initial and possible final drift states. In this way, the hole trajectories in phase space can be accurately traced. It is found that the average hole energies are significantly lower than the corresponding electron energies for the field strengths examined. This result is most probably due to the drastic difference in curvature between the uppermost valence bands and the lowest conduction band. The relatively flat valence bands impede hole-heating, leading to low average hole energy.

Polar optical phonon scattering and negative Krömer–Esaki–Tsu differential conductivity in bulk GaN

“…1) of the first BZ into fine tetrahedra, and store the band energies and the cell-periodic overlap parameters at the nodes of these tetrahedra. Even though the term # W j;m 0 ð W k 0 Þ is not confined to the IW, ZB and WZ point-group symmetry operations [8,9] can be applied to generate the images of the points in IW, and hence, the overall integration can essentially be performed exploiting the tetrahedra in IW. It needs to be mentioned that very fine division of the IW ($400,000 tetrahedra) is necessary to reduce the computational ripple, especially favoring the high-symmetry points where satellite valleys are present.…”

Comparative Assessment of GaN as a Microwave Source with Si and SiC for Mixed Mode Operation at Submillimetre Wave Band of Frequency

“…But they are based on simulation results of symmetric diode structures where the hole saturation velocity is assumed to be the same as the electron saturation velocity. This assumption is however incorrect in view of reports [4,5]. In report [4], Albrecht et al have used Monte Carlo simulations of electron transport based upon an analytical representation of the lowest conduction bands of bulk, wurtzite phase GaN to develop a set of transport parameters for devices with electron conduction in GaN.…”

“…In report [4], Albrecht et al have used Monte Carlo simulations of electron transport based upon an analytical representation of the lowest conduction bands of bulk, wurtzite phase GaN to develop a set of transport parameters for devices with electron conduction in GaN. On the other hand, in report [5], Oǧuzman et al have calculated the hole saturation velocity using an ensemble Monte Carlo simulator, including the full details of the band structure, and numerically determined phonon scattering rate based on empirical pseudopotential method. They found that the average hole energies are significantly lower than the corresponding electron energies believed to be due to the drastic difference in curvature between the uppermost valence bands and the lowest conduction band [5].…”

“…On the other hand, in report [5], Oǧuzman et al have calculated the hole saturation velocity using an ensemble Monte Carlo simulator, including the full details of the band structure, and numerically determined phonon scattering rate based on empirical pseudopotential method. They found that the average hole energies are significantly lower than the corresponding electron energies believed to be due to the drastic difference in curvature between the uppermost valence bands and the lowest conduction band [5]. The relatively flat valence band is responsible for hole heating, leading to low average hole energy and drastically low hole velocity compared to that for electrons.…”

The Optical Properties of Cubic III-Nitrides

“…This can be an advantage since InGaN layers with high In content show a strong tendency for In segregation. The smaller effective mass and the higher mobility of free carriers in III-nitrides [4] and their larger saturation drift velocity is advantageous for high temperature electronic device applications. Finally, c-III-nitrides are mainly grown on semiconductor substrates with cubic crystal structure allowing easy cleavage of laser facets and possible future integration of III-nitrides with the advanced GaAs (Si-technology).…”