COMPARISON OF ZN1-XMNXTE ZNTE MULTIPLE-QUANTUM WELLS AND QUANTUM DOTSBY BELOW-BANDGAP PHOTOMODULATED REFLECTIVITY/

Large-area high-density patterns of quantum dots with a diameter of 20 0 nm have been prepared from a series of four Zno(0.93)Mn(0.07)Te/ZnTe multiple quantum well structures of different well width (40 Angstrom , 60 Angstrom, 80 Angstrom and 100 Angstrom) by electron lithography f ollowed by Ar+ ion beam etching. Below-bandgap photomodulated reflecti vity spectra of the quantum dot samples and the parent heterostructure s were then recorded at 10 K and the spectra were fitted to extract th e linewidths and the energy positions of the excitonic transitions in each sample. The fitted results are compared with calculations of the transition energies in which the different strain states in the sample s are taken into account. We show that the main effect of the nanofabr ication process is a change in the strain state of the quantum dot sam ples compared with the parent heterostructures. The quantum dot pillar s turn out to be freestanding, whereas the heterostructures are in a g ood approximation strained to the ZnTe lattice constant. The lateral s ize of the dots is such that extra confinement effects are not expecte d or observed.