Aluminium photoluminescence

Electron spin resonance reveals the unpaired electrons associated with impurities or structural defects and can be used to identify the lattice site positions of these features. Nitrogen is shown to substitute for carbon and acts as a shallow donor. The various ESR triplets due to nitrogen in several SiC polytypes give information on the lattice sites occupied. For the acceptor boron, ESR shows it to occupy Si sites only, in disagreement with DAP photoluminescence measurements which show only boron on carbon sites. It may be that boron substitutes on both sites and the two techniques have sensitivity for only one particular lattice site. The aluminium acceptor is not observed in ESR but gallium has been noted in one report. Transition metals, Ti and V, have been identified by ESR both isolated on Si sites and in Ti-N complexes. Several charged vacancy defects have been assigned from ESR spectra in irradiated samples. 

The ionisation energies of the electronically active impurities have been determined primarily by photoluminescence techniques and Hall measurements. Ionisation energy levels of such impurities as nitrogen and some of the group III elements (aluminium, gallium, boron) in 3C-, 4H-, 6H- and 15R-SiC polytypes are compiled in TABLE 2. Nitrogen gives relatively shallow donor levels. In contrast, other p-type dopants have deep-level acceptor states. 

Other subjects recently discussed include the photocoabsorption of carbon monoxide and oxygen on ZnO,664 the relative photoabsorption of oxygen and methane over ZnO,665 the photocatalytic properties of ZnO and MgO,66 the effect of irradiation on the dielectric properties of Ti02,667 the photoluminescence of an oxide layer on aluminium,668 the singlet-triplet splitting of the free A-exciton in ZnO,659 the properties of the photosensitive film of copper in iodine solution,580 and the photosensitivity of layers of CuCla and [Fe(ox)8]3-.681... 

Steiner P, Kozlowski F, Wielunski M et al (1994) Enhanced blue-light emission from an indium-treated porous sihcon device. Jpn J Appl Phys 33 6075-6077 Stievenard D, Deresmes D (1995) Are electrical properties of an aluminium-porous silicon junction governed by dangling bonds Appl Phys Lett 67 1570-1572 Sze SM (1985) Semiconductor devices physics and technology. Wiley, New York Tsai C, Li KH, Sarathi J et al (1991) Thermal treatment studies of the photoluminescence intensity of porous silicon. Appl Phys Lett 59 2814-2816... 

Photoluminescence characteristics of rare earth-dopred nanoporous aluminium oxide, A-ppl. Surf. Sci. Vol 234, p.457-461. 

Lu C.H., Hong H.C., Jagannathan R. Sol-gel synthesis and photoluminescent properties of cerium-ion doped yttrium aluminium garnet powders. J. Mater. Chem. 2002 12 2525-2530 Marsh P.J., Silver J., Vecht A., Newport A. Cathodoluminescence studies ofyttrium silicate cerium phosphors synthesized by a sol-gel process. J. Lumin. 2002 97 229-236 Meyer F., Hempehnann R, Mathur S., Veith M. Microemulsion mediated sol-gel synthesis of nano-scaled MAI2O4 (M = Co, Ni, Cu) spinels from single-source heterobimetallic alkoxide precursors. J. Mater. Chem. 1999 9 1755-1763... 

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