Near band-edge optical properties of cubic GaN with and without carbon doping
We report the results of studying the optical properties of cubic GaN thin films with photoluminescence and photoluminescence excitation spectroscopies. The films are deposited by plasma-assisted molecular beam epitaxy on GaAs (001) substrates, with and without intentional doping with carbon atoms (p-type doping). The evolution of the optical spectra of the C-doped samples is consistent with a picture in which carbon enters into N-vacancies at low concentrations, producing a marked improvement in the crystalline properties of the material. At higher concentrations it begins to form complexes, possibly due to interstitial occupation. The temperature dependence on the absorption edge of the doped material is also measured and is analyzed with standard theoretical models.
The near band edge photoluminescence of cubic GaN epilayers
The near band edge photoluminescence (PL) of cubic GaN epilayers grown by radio frequency (rf) plasma-assisted molecular beam epitaxy on (100) GaAs is measured. Since the PL is excited with an unfocused laser beam it resembles the layer properties rather than the properties of micron-size inclusions or micro crystals. The low temperature PL spectra show well separated lines at 3.26 and 3.15 eV which are due to excitonic and donor-acceptor pair transitions (donor binding energy 25 meV, acceptor binding energy 130 meV). No emission above the band gap of the cubic phase is detected. PL results are confirmed by x-ray diffraction and atomic force microscopy which reveal only negligible contributions from hexagonal inclusions and micron size single crystals. The room temperature PL consists of an emission band at about 3.21 eV with a full width at half maximum of 117 meV.
European Consumer Access to Justice Revisited
Part I. Setting the Stage: Access to Justice 2.0: 1. At the very outset 2. Access to justice 2.0: breaking it into pieces Part II. Procedural Law: The Traditional Pillar of Access to Justice 2.0: 3. A brief outline of the developments at the pan-EU level 4. Prime examples 5. Compensatory collective redress: the next step? 6. Where to go from here? Part III. Substantive Law: Complementing Access to Justice 2.0: 7. Widening the scope of the value-oriented justice discussion 8. Substantive consumer law-making in the course of time 9. Recent trends and developments 10. The common European sales law 11. Summarising comments on the defragmentation of substantive consumer laws in the context of the CRD and the CESL Part IV. Consumer Access to Justice 2.0: A Multidimensional Framework: 12. From the current state of consumer law to consumer access to justice 2.0 13. The justice debate and consumer legislation 14. (Responses to) counter-arguments to third-party intervention 15. Consumer empowerment 16. Lessons to be drawn.