Studies Of Growth And Luminescent Properties In Self-organized InAs Quantum Dots

Semiconductor materials with self-organized quantum dot structure play a very important role in photoelectronic and microelectronic field. It is a good candidate for the high quality photoelectronic and microelectronic devices, such as fiber optical communication lasers, photoelectronic detectors, high electron mobility transistors and electro-optic modulators. Among the kinds of method to fabricate the semiconductor quantum dots, self-organized processes is the one of most efficiency methods and attracted significant interest. The studies of growth and physical property of self-organized quantum dots has become one of hot topic in reduced dimensionality physical system. In this paper Photoluminescence (PL) spectra and time-resolved spectra were applied to study InAs quantum dots. And we have got some significative results. Main works and results include:(1) . Growth method of self-organized quantum dots was studied. High quality InAs self-organized quantum dots were grown by MBE (molecular beam epitaxy) technique. Structure and pattern of Quantum dots were characterized by atomic force microscopy (AFM).(2) . InAs Quantum dots and wetting layer were studied and compared by using photoluminescence and time-resolved spectrum. Luminescent mechanics model of InAs quantum dots and wetting layer were presented, and it explained our results well.(3) . InAs quantum dots covered with InGaAs buffer and with AlAs buffer were measured by PL and TRS spectra. The broadening and intensity of Photoluminescence (PL) varying with temperature were studied. It was foundthat PL intensity of InAs quantum dots would increase when InGaAs or AlAs buffer were added among the growth of InAs quantum dot. Red shift of PL spectra peak was observed, and PL lifetime would rise at the same time. Two orders decline of Photoluminescence was caused by quantum with different stress and different sizes.(4) . It was found that multi-layer cycle growth method is propitious to increase quantum dots' uniformity and PL Intensity and reduce the full width of half maximum (FWHM) of PL peaks. FWHM and lifetime of this kind of quantum dots was little affected by temperature. The PL wavelength of InGaAs-covered quantum dots was much longer than common quantum dots. This result hinted a way to obtain the materials with longer wavelength luminescence. The lifetime and mechanics of PL are researched by FL920 time resolved measurement system. It indicated that PL lifetime of quantum dots is greater than those of bulk material and quantum well.