Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Optical properties of as-grown and annealed InAs quantum dots on InGaAs cross-hatch patterns | Himwas et al. Nanoscale Research Letters 2011 6 496 http content 6 1 496 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Optical properties of as-grown and annealed InAs quantum dots on InGaAs cross-hatch patterns Chalermchai Himwas Somsak Panyakeow and Songphol Kanjanachuchai Abstract InAs quantum dots QDs grown on InGaAs cross-hatch pattern CHP by molecular beam epitaxy are characterized by photoluminescence PL at 20 K. In contrast to QDs grown on flat GaAs substrates those grown on CHPs exhibit rich optical features which comprise as many as five ground-state emissions from 1-10 - and 110 -aligned QDs two wetting layers WLs and the CHP. When subject to in situ annealing at 700 C the PL signals rapidly degrades due to the deterioration of the CHP which sets the upper limit of overgrowth temperature. Ex situ hydrogen annealing at a much lower temperature of 350 C however results in an overall PL intensity increase with a significant narrowing and a small blueshift of the high-energy WL emission due to hydrogen bonding which neutralizes defects and relieves associated strains. Keywords quantum dots cross-hatch patterns photoluminescence annealing InAs InGaAs. Introduction Self-assembled InGaAs quantum dots QDs have been intensively investigated during the last decade due to their high crystalline quality 1 . InGaAs QDs conventionally grown on on-axis 100 -GaAs substrates are optically active and typically emit in the to eV range 2 . Those grown unconventionally - on high-index substrates 3 pre-patterned layers 4 or crosshatch patterns 5-9 - exhibit similar optical characteristics with a possibility to obtain lateral QD alignment further expanding the range of optoelectronic applications which includes lasers 10 and detectors 11 . These QDs are usually embedded in a junction mirror structure and have to be overgrown by GaAs or AlGaAs. The active QD and overgrown layers however have different growth .
