Browsing by Subject "Polar optical phonon scattering"

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Open Access
High-energy electron relaxation and full-band electron dynamics in aluminium nitride
(Elsevier, 2002) Bulutay, Ceyhun; Ridley, B. K.; Zakhleniuk, N. A.
Material properties of AlN, particularly its wide band gap around 6 eV, warrant its operation in the high-field transport regimes reaching MV/cm fields. In this theoretical work, we examine the full-band scattering of conduction band electrons in AlN due to polar optical phonon (POP) emission, which is the main scattering channel at high fields. First, we obtain the band structure for the wurtzite phase of AlN using the empirical pseudopotential method. Scattering rates along the full length of several high-symmetry directions are computed efficiently through the Lehmann-Taut Brillouin zone integration technique. In order to shed light on the behaviour of the velocity-field characteristics at extremely high electric fields, in the order of a few MV/cm, we resort to an Esaki-Tsu estimation. Comparison of these results for AlN is made with our similar work on GaN. With typically more than 50% higher POP scattering rate compared to GaN, AlN has poorer high-field prospects. Availability of these data for AlN and GaN paves the way for practical assessment of the high-energy electron dynamics for the ternary alloy, AlGaN.
Open Access
Scattering analysis of two-dimensional electrons in AlGaN/GaN with bulk related parameters extracted by simple parallel conduction extraction method
(American Institute of Physics, 2010-07-15) Lisesivdin, S. B.; Yildiz, A.; Balkan, N.; Kasap, M.; Ozcelik, S.; Özbay, Ekmel
We carried out the temperature (22-350 K) and magnetic field (0.05 and 1.4 T) dependent Hall mobility and carrier density measurements on Al 0.22Ga0.78N/GaN heterostructures with AlN interlayer grown by metal-organic chemical-vapor deposition. Hall data is analyzed with a simple parallel conduction extraction method and temperature dependent mobility and carrier densities of the bulk and two-dimensional (2D) electrons are extracted successfully. The results for the bulk carriers are discussed using a theoretical model that includes the most important scattering mechanisms that contribute to the mobility. In order to investigate the mobility of two-dimensional electron gas, we used a theoretical model that takes into account the polar optical phonon scattering, acoustic phonon scattering, background impurity scattering, and interface roughness scattering in 2D. In these calculations, the values are used for the deformation potential and ionized impurity density values were obtained from the bulk scattering analysis. Therefore, the number of fitting parameters was reduced from four to two. © 2010 American Institute of Physics.