| Doping erbium into silicon promises advanced applications in novel solid state lasers and optical amplifiers. The greatest attribute of this approach lies in the intra-4f electronic transition ( 4I13/2 to 4I 15/2) of Er3+ which produces light emission at 1.54 mum, a wavelength falling in the window of minimal loss for silica optical fibers used in optical communications. Co-doping impurities, such as C, N, O and F, into Si:Er has been found to be an effective way for alleviating the problem associated with the forbidden nature of the 4I 13/2--4I15/2 atomic transition. Many research efforts have been devoted to understanding the effects of codopants, but the role played by these co-doped impurities in improving Er optical activities remains to be an issue in debate.; This thesis attempts to address the issue through a systematic investigation of Er lattice locations and their evolution with thermal annealing and in the presence of co-doped impurities. The work, largely based on ion channeling in crystals, shows that Er, if doped in Si via ion implantation, can mainly occupy two lattice locations, i.e., the tetrahedral (T) interstitial site and the hexagonal (H) interstitial site, depending on heat treatments and co-doped impurity contents. Despite their differences, four kinds of codopants (C, N, O and F) studied in the work give rise to strikingly similar effects on the occupation of Er lattice locations: to promote and stabilize Er on the H site as opposed to the case of codopant-free Si:Er. It is proposed in the thesis that interactions among Er, co-doped impurities, and crystal defects are critical for determining Er lattice locations in Si. The work has suggested two configurations with different symmetry (involving T-site or H-site Er) for optically active Er centers in 0 or C co-doped Si:Er for which a large body of optical and electrical data is available in the literature. In addition, the work provides a basis for understanding the great disparity existing in experiments and theories regarding the Er lattice sites in Si.; Finally, the thesis presents ion beam analysis for the determination of the tin to indium ratio in indium-tin oxide (ITO), a material frequently used in fabrication of solid state light emitting devices. In particular, the work demonstrates the advantages of high-resolution Rutherford backscattering (HRRBS) with a magnetic spectrometer for charged particle detection. |
