Optical Characterization of Tensile Strained Germanium and Gallium Arsenide Quantum Dots

Strain as an additional knob in quantum dot growth offers the ability to tailor a material for sensors or quantum applications like quantum communication in the standard telecommunication bands. Here we are investigating tensile strain germanium and gallium arsenide quantum dots for tuning their optical transitions into and across the mid infrared spectral region, gathering correlations between strain and confinement that define the quantum dots’ optoelectronic properties. With strain many semiconductors’ properties can be tailored. Indirect bandgap materials like germanium can be tuned into direct bandgap materials. With photoluminescence and Fourier-transform infrared spectroscopy we determine the nature of these quantum dots, illuminating band gap characteristics, emission efficiencies, and other optoelectronic properties. Preliminary results indicate a direct emission from the strained quantum dots. Using resonate Raman spectroscopy the percent strain a quantum dot undergoes from the host material is measured. The interplay between strain and confinement through their effects on optical response is mapped and an overall correlation is derived.