Impurity-based infrared emitters in silicon

Abstract

In the past few years significant progress has been made towards silicon-based lasers. Because of indirect band structure, optical band-gap transitions are not allowed in bulk silicon. Numerous approaches were proposed to overcome this difficulty in the near infrared wavelength range, such as silicon nanocrystals, Si/SiO2 and Si/SiGe superlattices, porous silicon, erbium-doped silicon and silicon light-emitting diodes. Recently, an infrared 1.67 µm silicon laser based on stimulated Raman scattering has been reported. The first silicon laser was realized in terahertz range by infrared optical excitation of group-V donor centres embedded in a silicon host lattice. This laser uses direct optical transitions between atom-like states of the shallow donors attached to the bottom of the silicon conduction band. Terahertz Stokes silicon laser, recently announced, employs the combined light scattering on impurity centres, whose excited 1s(E) and ground 1s(A1) states are resonantly coupled by an intervalley transverse acoustic phonon.