John Bomback

Formation of buried TiN in glass by ion implantation to reduce solar load

Ti and N were implanted into soda lime glass to doses up to 4.5×1017 cm−2 to reduce solar load and infrared transmission. Analysis of the Ti+N implant distributions by Rutherford backscattering spectrometry and x‐ray photoelectron spectroscopy (XPS) revealed profiles which closely followed each other as designed by the selection of implant energies. XPS, x‐ray diffraction, and selected area electron diffraction in transmission electron microscopy also confirmed the existence of a crystalline B1‐type, cubic TiN layer, 140 nm wide, at doses greater than 9×1016 cm−2. Optical measurements showed that the fraction of infrared radiation reflected was increased by almost a factor of 4 compared to an increase of 1.8 in the visible region. The percentage of the total solar energy rejected reached 80% at the highest dose, indicating that the buried TiN layer is highly effective in reducing solar energy transmission.

Characterization of ion implanted silicon: correlation of optical measurements with microstructural observations

Abstract Laser, electron and ion beam techniques were used to probe the near surface crystallography of silicon implanted with various ion species. Optical third harmonic radiation (THR) generated in reflection with short laser pulses was found to be a sensitive monitor of lattice damage. The isotropic part, or the part of the third harmonic signal which does not vary with crystalline orientation, reaches a minimum value at a critical ion dose and increases slightly at higher doses. The anisotropic part, or the part which exhibits the symmetry of the lattice, becomes negligible at the critical dose and remains so at higher doses. The critical dose depends on the mass and energy of the implanted ion. The consquences of making the measurements in air as opposed to making them in vacuum are discussed. Transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and ion channeling were used to correlate the nonlinear optical response (the intensity and polarization of the generated THR) with the near surface microstructure. Samples with the critical ion dose exhibited an amorphous layer containing residual crystalline particles near the surface. As the dose increases above the critical level the residual crystallites disappear and the surface layer becomes completely amorphous. Further implantation has no effect on the nonlinear response.

Optical properties of Ti and N implanted soda lime glass

Soda lime glass was implanted sequentially with Ti+ and N+ to doses ranging from 2 to 30×1016 cm−2 in order to study the resulting optical properties. Analysis of the implant distributions was made by using Rutherford backscattering and x‐ray photoelectron spectroscopy and revealed profiles which closely followed each other as designed by the selection of implant energies. Analysis of optical properties showed that the highest dose resulted in an increase in the fraction of infrared reflected by more than a factor of 4 versus 1.7 for the visible regime. The percentage of the total solar radiation rejected exceeded 60% at the highest dose, indicating that the buried layer is highly effective in reducing solar load.

Implantation of Ti and N into soda lime glass to minimize solar load and reflectivity

Abstract Soda lime glass was given two types of implantations; Ti followed by N to doses up to 4.5 × 1017 cm−2 to reduce solar load and IR transmission, and Ti to doses of 8.2 × 1016 cm−2 to reduce reflectivity of visible light. Analysis of the Ti + N implant distributions by RBS and XPS revealed profiles which closely followed each other as designed by the selection of implant energies. XPS and X-ray diffraction also confirmed the existence of B1-type, cubic TiN phase at doses greater than 9 × 1016 cm−2. Optical measurements showed that the fraction of infrared radiation reflected can be increased by almost a factor of 4 compared to an increase of 1.8 in the visible region. The percentage of the total solar energy rejected reached 80% at the highest dose, indicating that the buried TiN layer is highly effective in reducing solar energy transmission. The reflection of light in the visible region can be decreased by up to 43% by implantation of 150 keV Ti+ to a dose of 8.2 × 1016 cm−2. The change is most effective at 0° incidence and increases with dose.