Superlattices photoluminescence

Keywords Silicon, germanium, carbon, alloys, nanostructures, optoelectronics, light emission, photoluminescence, electroluminescence, quantum well, quantum wire, quantum dot, superlattices, quantum confinement. 

Arakawa, T., Watabe, H., Nagamune, Y., and Arakawa, Y., Fabrication and microscopic photoluminescence imaging of ridge-type InGaAs quantum wires grown on a (110) cleaved plane of AlGaAs/GaAs superlattice. Appl. Phys. Lett. 69,1294 (1996). 

Crystalline and amorphous silicons, which are currently investigated in the field of solid-state physics, are still considered as unrelated to polysilanes and related macromolecules, which are studied in the field of organosilicon chemistry. A new idea proposed in this chapter is that these materials are related and can be understood in terms of the dimensional hierarchy of silicon-backbone materials. The electronic structures of one-dimensional polymers (polysilanes) are discussed. The effects of side groups and conformations were calculated theoretically and are discussed in the light of such experimental data as UV absorption, photoluminescence, and UV photospectroscopy (UPS) measurements. Finally, future directions in the development of silicon-based polymers are indicated on the basis of some novel efforts to extend silicon-based polymers to high-dimensional polymers, one-dimensional superlattices, and metallic polymers with alternating double bonds. 

Earlier, the lifetime of charge carriers in GaAs superlattices was determined from the time-resolved photoluminescence spectra [3]. Changes in the total and radiative lifetimes were analyzed in the model with no k-selection rule and possible broadening effects. In spite of this, the predictions agree qualitatively with the observed increasing of the lifetime within the red shift of the decaying luminescence spectra. 

The major attention is given to the conqjensated GaAs superlattices with the layer thickness of 40 nm and concentration of donors and acceptors of 10 cm. The superlattice named No. 4i contains i-layers n-i-p-I stracture) and No. 4 means no i-layers n-p-n-p stmcture). Both structures belong to the long-period doping superlattices and their photoluminescence properties were measured in a wide temperature range. Pronounced effects of a-irradiation were observed [7]. 

Redistribution of the space-charge of the excited carriers is presented in Fig. 1. Therewith at low temperatures, as seen in Fig. 2, the tunable photoluminescence band maximum coincides with the difference of the quasi-Fermi levels AF, which in turn is close to the effective energy gap Eg of the doped superlattice. At... 

In this chapter we review the work done in our laboratory on the structure (Part II), optical absorption (Part III), photoluminescence (Part IV), and electrical transport (Part V) of a-Si H/a-SiNjci H superlattices. Results with single quantum well structures are discussed by Kukimoto in Chapter 12 of Volume 2ID. 

Conjugated polymer superlattices and porphyrin arrays connected with molecular wires are superstructured materials, which exhibit unique optical and photonic functions. The former shows a shift in photoluminescence to higher energy which is interpreted as a quantum size effect. The latter class of materials exhibits photoconductivity by a hole carrier mechanism and photoinformation storage by a localized excitation mechanism. The syntheses of these two classes of materials are described. 

In addition to the routine characterization of these copolymers with UV-visible, near IR and FTIR spectroscopy, XPS, elemental analysis and four-point probe conductivity measurements, Mossbauer [17] and photoluminescence (PL) [18,19] spectroscopy of the copolymer were used. When the thiophene content in the copolymer is higher than 50 mole%, there are three peaks at 2.0, 1.8 and 1.7 eV in the PL spectra of the copolymer. Below 50 mole%, the copolymer does not exhibit photoluminescence. Details of the fabrication of a type II conducting polymer heterolayer superlattice by the electrochemical copolymerization of pyrrole and bithiophene by the potential-programmed electropolymerization (PPEP) method are given in a recent review [19]. 

ABSTRACT. Band calculated results for electronic structures of sigma-conjugated polymers are reviewed. Conformational and substitutional effects for polysilanes are calculated theoretically and are discussed in the light of experimental data from UV absorption and photoluminescence. The electronic structures of hetero-copolymers of polysilane and polygermane, corresponding to the 1-dimensional superlattice structure, are described. Two-dimensional silicon network polymers are studied theoretically and experimentally. 

RG Alonso, E Oh, AK Ramdas, H Luo, N Samarth, JK Furdyna, LR Ram-Mohan. Raman and photoluminescence spectra of Zni-j,Cd ,Se/Zn, 3Mn3,Se—A diluted-magnetic-semiconductor superlattice. Phys Rev B 44 8009-8016, 1991. 

H Ozaki, D Suzuki, K Imai, K Kumazaki. Photoluminescence and Raman-scattering of ZnSe-ZnTe superlattices. Phys Status Solidi (a) 133 523-532, 1992. 

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