Application of Sub-second Annealing for Diluted Ferromagnetic Semiconductors

The dilute ferromagnetic semiconductor GaMnAs provides a great promise for its application in spintronics, which combines two degrees of freedom: charge and spin. Mn ions which substitute Ga sublattice sites provide both local magnetic moments and itinerant holes. The magnetic properties of GaMnAs can be controlled by manipulating free carriers via electrical gating. However, the preparation of ferromagnetic GaMnAs presents a big challenge due to the low solubility of Mn in GaAs. To overcome the low solid solubility limit of transition metal dopants in semiconductors, one needs highly nonequilibrium methods to introduce enough dopants and a short-time annealing to activate them. Both ion implantation and pulsed-laser (or flash-lamp) annealing occur far enough from thermodynamic equilibrium conditions. Ion implantation introduces enough dopants. The subsequent short-time annealing deposits energy in the near-surface region to drive a rapid liquid-phase epitaxial growth. Such a nonequilibrium process maintains the supersaturation induced by ion implantation. In this chapter, we review the application of sub-second annealing in the activation of Mn implanted GaAs as well as GaP.