Issue Eur. Phys. J. B Volume 69, Number 3, June I 2009 Page(s) 321 - 329 Section Solid State and Materials DOI 10.1140/epjb/e2009-00166-7 Published online 08 May 2009

Eur. Phys. J. B 69, 321-329 (2009)
DOI: 10.1140/epjb/e2009-00166-7

Electron mobility in wurtzite nitride quantum wells limited by optical-phonons and its pressure effect

Y. Qu and S.L. Ban

School of Physical Science and Technology, Inner Mongolia University Hohhot 010021, P.R. China

slban@imu.edu.cn

Received 18 December 2008 / Received in final form 19 March 2009 / Published online 8 May 2009

Abstract
Based on the dielectric continuum phonon model, uniaxial model and force balance equation the mobility of two dimensional electron gas in wurtzite Al_xGa_1-xN/GaN/Al_xGa_1-xN quantum wells is discussed theoretically within the temperature range dominated by optical phonons. The dependences of the electron mobility on temperature, Al molar fraction and electron sheet density are presented including hydrostatic pressure effect. The built-in electric field is also taken into account. It is found that under normal pressure the main contribution to the mobility is from the scattering of interface optical phonons in narrow (for well width d < 12 Å) and wide (for d > 117 Å and d > 65 Å for finitely thick barriers and infinitely thick ones, respectively) wells, whereas that is from the scattering of confined optical phonons in a well with an intermediate width. It is shown that the electron mobility decreases with increasing Al molar fraction and temperature, whereas increases obviously with increasing electron sheet density. The theoretical calculated electron mobility is 978 cm²/V s which is higher than an available experimental data 875 cm²/V s when x equals to 0.58 at room temperature. The results under hydrostatic pressure considering the modification of strain indicate that the mobility increases slightly as hydrostatic pressure increases from 0 to 10 GPa.

PACS
63.20.Kd - Phonon-electron interactions.
72.10.Di - Scattering by phonons, magnons, and other nonlocalized excitations.
73.63.Hs - Quantum wells.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2009

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