Phonon-limited electron mobility in III-nitride heterojunctions

• Phonon-limited electron mobility in GaN, InN and AlN heterojunctions (HJs) studied.
• Ritz iterative technique used.
• Inelastic (quasi-elastic) scattering due to optical (acoustic) phonons considered.
• Mobility dominated by acoustic phonons for T < 150 K and later by optical phonons.
• Good fit to recent experimental data for Hall mobility in GaN/AlGaN HJ obtained.

Low-field electron mobility limited by phonons in GaN-, InN- and AlN-based heterojunctions (HJs) for temperatures T < 300 K is studied within the framework of Boltzmann transport formalism by an iterative method. Electrons are assumed to occupy the lowest subband and scattered by the inelastic polar LO phonons and by quasi-elastic acoustic phonons through the deformation potential and piezoelectric couplings. Numerical calculations of the energy dependence of the first-order perturbation distribution function ϕ(E) for the polar LO phonons and of the acoustic phonon relaxation rates τ− 1(E) bring out the characteristic features of phonon scattering in nitride HJs. The temperature and concentration dependences of phonon-limited mobility are compared with the low-temperature and high-energy relaxation time approximations, commonly used for ϕ. Calculations, taking into account other relevant scattering mechanisms, obtain good agreement with available Hall mobility data for GaN/AlGaN HJ.

Temperature dependent phonon-limited electron Hall mobility, μH in GaN/AlGaN heterojunction sample of Zanato et al. [Semicond. Sci. Technol. 19, 427 (2004)], calculated using iterative technique and compared with low-temperature (LT) and high-energy (HE) relaxation rate approximations.Figure optionsDownload as PowerPoint slide