Shizuo Fujita

In Situ Monitoring And Control For MBE Growth Of Optoelectronic Devices

Self-organized CdSe/ZnSe quantum dots (QDs) were fabricated on the cleavage-induced GaAs (110) surface in ultra high vacuum (UHV) by molecular beam epitaxy (MBE). CdSe layer showed the Stranski¿Krastanow (S-K) growth mode. QWs and QDs emissions originated from the wetting layer and island structures, respectively, were observed in photoluminescence (PL) spectra. This is a evidence of S-K type where island structures are self-formed on the two-dimensional wetting layer as a result of the transition of the growth mode. The state filling effect in the QDs was also observed by employing excitation power dependence on the PL intensity. By using the microscopic PL spectroscopy, the broad PL peak of QDs was resolved into a number of sharp peaks. These peaks are attributed to the recombination of excitons localized at the individual QDs indicating that the fabricated CdSe islands have quasi-zero-dimensional δ-function like density of states.

Self-Organizing Process Of Moderately Strained Zn/sub 1-x/Cd x Se Layer Grown On GaAs

Fabrication of semiconductor nanostructures such as quantum wires and quantum dots is very important for realization of new functional quantum devices. Among the various methods, a self-organization technique using the Stranski-Krastanow (S-K) growth mode in strained system has received great interest because high quality nano-scaled islands can be easily formed by epitaxial growth without any minute lithographic processes. However, since the spatial distributions of these islands are random, it is difficult to obtain a precise control of characteristics of the device. Several groups have attempted to control the islands to be linearly ordered. However, only irregular short-range arrays (less than 1 pm) were obtained [1,2].