摘要
We present an experimental setup capable of time resolved photoluminescence spectroscopy for photon energies in the range of0.51 to 0.56 eV with an instrument time response of75 ps.The detection system is based on optical parametric three wave mixing,operates at room temperature,has spectral resolving power,and is shown to be well suited for investigating dynamical processes in germanium-tin alloys.In particular,the carrier lifetime ofa direct-bandgap Ge1-xSnx film with concentration x=12.5%and biaxial strain-0.55%is determined to be 217±15 ps at a temperature of 20 K.A room-temperature investigation indicates that the variation in this life-time with temperature is very modest.The characteristics of the photoluminescence as a function of pump fuence are discussed.
