Anisotropy and strain effects on lattice dynamics in nitride-based superlattices

• Published in: Physica status solidi. A, Applied research Applied research, 2003-02, Vol.195 (3), p.605-611
• Main Authors: GLEIZE, J, FRANDON, J, RENUCCI, M. A
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Iii-v and ii-vi semiconductors; Infrared and raman spectra and scattering; Lattice dynamics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Phonon states and bands, normal modes, and phonon dispersion; Phonons and vibrations in crystal lattices; Phonons in low-dimensional structures and small particles; Physics
• ISSN: 0031-8965; 1521-396X
• DOI: 10.1002/pssa.200306160

The lattice dynamics of quantum wells and superlattices made up of group Ill-nitride semiconductors [GaN/AlN, GaN/(Al,Ga)N] with wurtzite structure is discussed with emphasis on polar phonons accessible to Raman spectroscopy. A macroscopic model is developed to describe the static equilibrium of GaN/AlN superlattices in free-standing state and to analyze the influence of spontaneous and piezoelectric polarizations on the strain in the constituent layers. The main electrostatic effect concerns the strain component along the growth axis, which can be significantly reduced, particularly in the AlN layers. A phenomenological approach to superlattice polar phonons based on a dielectric continuum model is used to calculate the angular dispersion of quasi-confined modes in a strained GaN/AlN superlattice. It fairly reproduces the experimental results obtained by Raman spectroscopy.