Effects of rapid thermal anneal on refractive index and hydrogen content of plasmaenhanced chemical vapor deposited silicon nitride films Amorphous silicon produced by ion implantation: Effects of ion mass and thermal annealing
Room-temperature near-infrared reflection and transmission measurements on GaAs ion implanted at 2.7 MeV with a fluence of 6.4×1016 P+/cm2 showed amplitude-modulated interference fringes. The reflection fringes were analyzed by using a simple model in which the implanted material is approximated by two partially absorbing layers on a nonabsorbing substrate. The analysis results indicate that the effective layer thicknesses are comparable with those predicted by the projected ion range and the width of the Gaussian ion distribution. The implantation-induced damage produces an increase in the refractive indices. The observed increase in the absorption is similar to that previously reported for GaAs which has been implanted at lower energy.
Characterization of the two optical states of amorphous Si produced by ion implantation is extended to include electron paramagnetic resonance, fundamental absorption edge, and density measurements in addition to infrared reflection. It is found that the properties of the two a-Si states are not dependent upon the mass of the incident ion (12C, 29Si, 31P, 120Sn) or upon the anneal temperature for 400 °≤TA≤600 °C. The dangling-bond density drops about a factor of 2 when the a-Si makes a transition between the two states. The absorption coefficient also drops by more than a factor of 5, but the density of the a-Si does not change when the transition occurs. The transition between states was not completed at TA=300 °C, so the annealing mechanism may be temperature dependent.
A model-dependent computer analysis technique developed previously has in this work been applied to the infrared reflection data of a number of < 111 > and < 100> oriented Si samples which were implanted with high fluences ofSi or P ions and then taken through an isothermal annealing process. The physical properties deduced from this analysis are: (i) Dielectric properties including the frequency dependent refractive indices of the recrystallized Si and of the a-Si as a function of annealing temperature and time; (ii) structural information including the amorphous layer depth, widths of transition regions, and the epitaxial regrowth rates; and (iii) electrical properties including the depth profile of the carrier density, the carrier mobility near the maximum carrier density, and the carrier activation efficiency. The physical interpretation ofthe results is discussed and, where possible, comparisons with results of other experiments are made.
Absorption saturation in germanium, silicon, and gallium arsenide at 10.6 μm Appl.The infrared absorption of GaAs doped with 2sSi, 30Si, or 2sSi + 3Dgi and compensated by 6Li diffusion or electron irradiation is reported. Isotopic shifts close to those predicted from local-mode theory are observed for all the silicon defect bands in 30Si-doped GaAs from frequencies previously reported for 2sSi_doped material. a new band is observed at 456 cm-I for the sample containing both 2sSi and 30Si, and is attributed to e S Si-3 Dgi) pairs. The frequency of the new band is in accord with simple theory, and its presence confirms the observation of the nearest-neighbor silicon pairs. The results indicate, however, that the indentification of one of the three absorption bands previously attributed to the 2sSi pairs is questionable. The experimental result also indicates that an absorption band at 369 cm -I previously observed in electron-irradiated samples is indeed due to a silicon-related defect.
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