Electron spin dynamics in GaN

• Published in: Physica Status Solidi. B: Basic Solid State Physics Vol. 251; no. 9; pp. 1850 - 1860
• Main Authors: Rudolph, Jörg, Buß, Jan Heye, Hägele, Daniel
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01.09.2014
• Subjects: Dynamics; Electron spin; Gallium nitrides; Localization; Position (location); Semiconductors; Spin dynamics; Wurtzite
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201350185

Gallium nitride is a promising material system for spintronics, offering long spin relaxation times and prospects for room‐temperature ferromagnetism. We review the electron spin dynamics in bulk GaN. Time‐resolved magneto‐optical studies of both the wurtzite and the cubic phase of GaN show the dominance of Dyakonov–Perel (DP) relaxation for free conduction band electrons. Spin relaxation in the wurtzite phase is characterized by an intrinsic spin relaxation anisotropy and the limitation of spin lifetimes by a strong Rashba term. Spin lifetimes are strongly enhanced in cubic GaN, where only a weak Dresselhaus term contributes to DP relaxation. Ion‐implanted wurtzite GaN shows a strong increase of electron spin lifetimes for increasing implantation dose, caused by increasing localization of carriers. The spin dynamics of conduction band electrons in Gd‐implanted GaN as a candidate for a room‐temperature ferromagnetic semiconductor is also only governed by localization effects and does not show signs of an efficient exchange coupling between the electrons and the magnetic Gd ions. In this Feature Article, an overview of the electron spin dynamics in bulk GaN is given. Special emphasis is put on the comparison of spin relaxation in wurtzite and cubic GaN, exemplarily illustrating the dominating role of crystal structure and, hence, symmetry of spin‐orbit coupling for the spin dynamics of delocalized electrons. The impact of localization on the spin dynamics is reviewed for ion‐implanted GaN.