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Advances in Light emitting Materials
- 2008
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- This special-topic volume‚ Advances in Light-Emitting Materials’, makes an important contribution to the field of silicon and III-nitride semiconductors. It begins with a brief history of visible-light emitting diodes. However, silicon is currently expanding from micro-electronics and into photonics. Due to its unsuitable band-gap, it has not previously been the material-of-choice for opto-electronic integration. That is now beginning to change and silicon devices have been developed which have the capability to emit, modulate, guide and detect light and which can be combined with microelectronics to form electronic and photonic integrated circuits. read more...In particular, the performance of silicon-based light-emitters has made rapid progress during the last few years: the first paper describes the potential value of the D-band luminescence caused by dislocations in silicon and its use in infra-red light-emitters. Silicon-wafer direct-bonding, which permits the controlled formation of dislocation networks, is described in detail in the next paper. Silicon and silicon-germanium light-emitting diodes (LED), which emit band-to-band radiation, are then described. This paper is followed by observations on the effect of carrier-confinement on the emission of the band-to-band radiation of LEDs fabricated in silicon-on-insulator form. Finally, MOS light-emitting devices, based upon rare-earth ion-implantation, are described. These structures exhibit efficient electroluminescence within the wavelengths ranging from UV to visible light.Altogether, this volume presents an in-depth review of this important topic.
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- Buyanova, Irina, 1960-, et al.
(författare)
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Effect of electron irradiation on optical properties of gallium nitride
- 1999
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T79, s. 72-75
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Tidskriftsartikel (refereegranskat)abstract
- The effect of electron irradiation on the optical properties of GaN epilayers is studied in detail by photoluminescence (PL) spectroscopy. The most common types of GaN material are used, i.e. strained heteroepitaxial layers grown on 6H SiC or Al2O3 substrates, and thick bulk-like layers with the conductivity varying from n-type to semi-insulating and p-type. The main effects of electron irradiation on all investigated samples are found to be as follows: (i) a radiation-induced quenching of excitonic emissions in the near band gap region; (ii) an appearance of broad overlapping PL emissions within the spectral range 0.7-1.1 eV and (iii) the appearance of a PL band with a sharp no-phonon (NP) line at around 0.88 eV followed by a rich phonon assisted sideband. The 0.88 eV band is shown to originate from an internal transition of a deep defect. With increasing temperature a hot PL line can be observed at about 2-4 meV above the NP line, originating from higher lying excited states of the defect. The electronic structure of the 0.88 eV defect is shown to be very sensitive to the internal strain field in the GaN epilayers.
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- Buyanova, Irina, 1960-, et al.
(författare)
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Effect of growth temperature on photoluminescence of GaNAs/GaAs quantum well structures
- 1999
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 75:24, s. 3781-
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Tidskriftsartikel (refereegranskat)abstract
- The effect of growth temperature on the optical properties of GaAs/GaNxAs1-x quantum wells is studied in detail using photoluminescence (PL) spectroscopies. An increase in growth temperature up to 580 °C is shown to improve the optical quality of the structures, while still allowing one to achieve high (>3%) N incorporation. This conclusion is based on: (i) an observed increase in intensity of the GaNAs-related near-band-edge emission; (ii) a reduction in band-edge potential fluctuations, deduced from the analysis of the PL line shape; and (iii) a decrease in concentration of some extended defects detected under resonant excitation of the GaNAs. The thermal quenching of the GaNAs-related PL emission, however, is almost independent of the growth temperature and is attributed to a thermal activation of an efficient nonradiative recombination channel located in the GaNAs layers.
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- Buyanova, Irina, 1960-, et al.
(författare)
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Electronic Properties of Ga(In)NAs Alloys
- 2001
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Ingår i: MRS Internet Journal of Nitride Semiconductor Research. - 1092-5783. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- A brief review on the present knowledge of the electronic properties of the Ga(In)NAs ternary and quaternary alloys is given mainly from an experimental perspective. The discussion is focused on Ga(In)NAs with low N composition (< 10 %), where a large amount of experimental work has been done. Important fundamental electronic properties of the material system are analyzed with the emphasis on the nature of the giant band gap bowing in the alloy and nitrogen-induced modifications of the electronic structure of the conduction band. The current knowledge of the key material parameters, relevant for the device applications, such as electron effective mass, recombination processes and band alignment in Ga(In)NAs/GaAs heterostructures, is also reviewed.
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- Buyanova, Irina, 1960-, et al.
(författare)
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Electronic structure of the 0.88-eV luminescence center in electron-irradiated gallium nitride
- 1999
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Ingår i: Physical review. B, Condensed matter and materials physics. ; 60:3, s. 1746-1751
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Tidskriftsartikel (refereegranskat)abstract
- Photoluminescence (PL) spectroscopy is employed to determine the nature of a near-infrared PL emission with a no-phonon line at ∼0.88 eV, commonly present in electron-irradiated GaN. This PL emission is suggested to originate from an internal transition between a moderately shallow excited state (with an ionization energy ∼21 meV) and the deep ground state (with an ionization energy ∼900 meV) of a deep defect. The existence of a higher-lying second excited state related to the 0.88-eV PL center is also shown from temperature-dependent studies. A different electronic character of the wave functions related to the first and second excited states has been revealed by PL polarization measurements. Since the PL emission has been observed with comparable intensity in all electron-irradiated GaN samples independent of doping on the starting material, it is proposed that either native defects, or common residual contaminants or their complexes are involved. The substitutional ON donor (or related complex) is considered as the most probable candidate, based on the observed striking similarity in the local vibrational properties between the 0.88-eV PL centers and the substitutional OP donor in GaP.
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