Type-I Optical Emissions In Ge/Si Quantum Dots

The authors studied the optical emission of Ge/Si quantum dots under externally applied biaxial stress using samples grown with different temperatures varying from 430 to 700 degrees C. The optical emission energy of samples grown at low temperatures is rather insensitive to the applied external stress, consistent with the type-II band alignment. However, for samples grown at high temperatures we observed a large blueshift, which suggests type-I alignment. The result implies that recombination strength can be controlled by the growth temperature, which can be useful for optical device applications. (c) 2007 American Institute of Physics.