Shell thickness induced strain effect on structure and optical properties of lattice matched HgTe/CdTe core/shell structure

Shell thickness dependent structure and optical properties of lattice matched epitaxially grown HgTe/CdTe core/shell nanocomposite is reported in this communication. High resolution electron microscope (HRTEM) images of the core/shell show increase of the nanocomposite size with increasing CdTe shell thickness and crystalline defect formation beyond 2.1 monolayer (mL) shell thickness, possibly due to compressive strain. Fluorescence (FL) spectra of the core/ shells showed increase of FL yield along with red shift and narrowing spectral width with increasing shell thickness up to 2.1 mL, due to (i) surface passivation, (ii) partial leakage of electron wave function of HgTe core to CdTe shell and (iii) narrowing size distribution. With further increase of CdTe shell thickness (beyond 2.1 mL), the FL intensity decreases due to compressive strain from the CdTe shell, the spectral width increases due to increase in size dispersion and the spectral position further red shifted due to compressive strain as confirmed from x-ray diffraction study. (author)