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

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

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

Corresponding author: ^a slban@imu.edu.cn

Received: 18 December 2008
Revised: 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.