Optical implants

Hydrogels were first developed as contact lenses or optical implants, and are usually composed of glycol methacrylates. Gels consist of insoluble polymers with aqueous, interactive, hydrophilic sites. The two basic types are (1) a flexible sheet, comprised of a 3-dimensional macro structure, that does not change physical form as fluid is absorbed but swells until equilibrium is reached, and (2) a non-fixed amorphous gel whose viscosity decreases as fluid is absorbed until the gel assumes the shape of the wound. In the latter case, the fluid continues to be absorbed until all cohesive properties are lost and the gel becomes a dispersion of the polymer in water (19). Several types of gels are available on the market but the properties are similar whether the product is in the form of a sheet or a gel. Hydrogels could be excellent... 

Wafer charging is becoming a critical issue as new MOS devices are designed with thinner (<10 mm) gate dielectrics. Lower energy implanters require optics that compensate for beam divergence which occurs at low energeries (32). 

Another basic approach of CL analysis methods is that of the CL spectroscopy system (having no electron-beam scanning capability), which essentially consists of a high-vacuum chamber with optical ports and a port for an electron gun. Such a system is a relatively simple but powerful tool for the analysis of ion implantation-induced damage, depth distribution of defects, and interfaces in semiconductors. ... 

The optical absorption spectra of Au-implanted silica samples annealed in air or Ar for 1 h at different... 

Figure 7. Optical absorption spectra of Au-implanted silica samples atmealed in air (a) or Ar (b) for 1 h at different temperatures, (c) Nonlinear fit (empty circles) to the optical absorption spectrum of the sample annealed at 900 °C in air, from which the average cluster diameter is obtained and compared to the TEM measured one, (d) Evolution of the optical spectra of Au-...

The TEM data have been used to simulate, in the frame of the Mie theory and Maxwell-Garnett effective medium approximation [15], the optical absorption spectra of the sample implanted with 5 x lO Au /cm. The results are reported in Figure 8(c). In the first model used to describe... 

Figure 8. TEM and optical absorption of the sample implanted with 5 x 10 Au /cm (a) TEM cross-sectional micrograph (dashed lines represent the free surface and film-substrate interface) (b) nanoparticles size distribution (c) simulated optical spectra (1) Au cluster in a non-absorbing medium with n = 1.6 (2) Au cluster in polyimide (absorbing) (3) Au(core)-C(shell) cluster in a nonabsorbing medium with n = 1.6 (4) the experimental spectrum of Au-implanted polyimide sample, (d) X-ray diffraction patterns as a function of the implantation fiuence.

Figure 17. Optical absorption spectra of the polyimide implanted with 5x 10 Au m in presence of dry air and of methanol vapor (6000 ppm). Inset optical absorption difference calculated taking into account both spectra. (Reprinted from Ref. [68], 2005, with permission from Elsevier.)...

Figure 18. Dynamical optical absorption responses for (a,c) the polyimide film implanted with 5 x 10 Au /cm and for (b,d) the virgin film obtained upon different exposures to (a,b) methanol vapors (6000 ppm) or (c,d) to ethanol vapors (6000 ppm).

Due to the small emission and absorption cross sections of Er +, a high Er density is needed to reach reasonable values of optical gain. Typically Er densities are between 0.1% and 1.0% (10 -10- Er/cm- ). These values are far beyond the equilibrium solubility limits of Er in silicon. Therefore, nonequilibrium methods have to be used, such as ion implantation. Er implantation in crystalline silicon leads to amorphization, and additional annealing (600°C) is required to... 

In this sub-subsection, the Er doping of amorphous silicon is discussed. The problem of limited solubility of Er in crystalline silicon has been circumvented. However, the electrical properties of pure a-Si are poor compared to c-Si. Therefore, hydrogenated amorphous silicon is much more interesting. Besides, the possibility of depositing a-Si H directly on substrates, i.e., optical materials, would make integration possible. Both low-pressure chemical vapor deposition (LPCVD) [664] and PECVD [665, 666] have been used to make the a-Si H into which Er is implanted. In both methods oxygen is intentionally added to the material, to enhance the luminescence. 

In this section we shall consider the results obtained by optical spectroscopy on GaAs, GaP and InP undoped bulk materials implanted with protons or deuterons, i.e., we shall not take into account the works on passivation in which implantation has been used as the technique for introducing hydrogen or deuterium. 

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