Excitation paths in RE-doped III–V semiconductors

Optical properties of III–V compound semiconductors are frequently engineered by doping with RE ions. In that way narrow emission bands with a temperature-independent wavelength can be obtained. In order to achieve intense luminescence, efficient and temperature-stable excitation mechanism, as well as suppression of nonradiative recombinations of the optical dopant is required. Investigation of these processes is usually done by analysis of thermal effects and by excitation spectroscopy. Recently, we have proposed that energy transfer mechanisms in optically doped semiconductor hosts can be conveniently studied using two-color experiments combining band-to-band pumping with spectral probing by a free-electron laser as a tunable source of mid-infrared radiation. In this paper, we review shortly some results obtained by this novel approach on InP:Yb, and discuss perspectives of future research.