Arthur C. Adams

Optical properties of low‐pressure chemically vapor deposited silicon over the energy range 3.0–6.0 eV

The optical properties of undoped and P‐doped silicon prepared by low‐pressure chemical vapor deposition were measured by spectroscopic ellipsometry over the energy range 3.0–6.0 eV. A marked effect of material microstructure is observed. Approximate values of the density deficit and of the volume fractions of crystalline and amorphous material are estimated as components of the microstructure by comparing measured spectra to those synthesized from constituent spectra in the Bruggeman effective‐medium approximation.

Optical properties of LPCVD aB (H)

Abstract Amorphous boron-hydrogen alloys (9 to 24 at % H) have been prepared and optical properties determined. In the ir, the only bands observed involving H are the B-H stretch at 2560 cm−1 and the B-H bend at 1108 cm−1; no evidence is found for bands associated with BH2 groupings or H three-center bonds. In the visible-near uv, the ϵ2 spectrum for the sample with 9 at % H has a broad maximum near 5eV with a peak value of 6. With increasing H content, both optical gap and ϵ2 peak move to higher energies, while the ϵ2 peak value and refractive index decrease.

Optical Characterization of Chemically Vapor Deposited and Laser-Annealed Polysilicon

The optical properties of polysilicon on insulating SiO 2 were measured by spectroscopic ellipsometry over the energy range 3.0 to 6.0 eV. Spectra were obtained for films as-deposited and after irradiation with an Ar ion laser (focused to a 50μm spot diameter) at 6.0, 7.0 or 7.5 watts. We observed monotonic changes in both e1 and e2 with increasing incident power even though the power density was high enough to completely melt the silicon surface in all cases. The changes observed are caused by changes in microstructure; with increasing power the amorphous component decreases and the density increases. Approximate values of the microstructural components are estimated by comparing measured spectra to those synthesized from constituent spectra in the Bruggeman effective medium approximation.

Surface chemical reactivity of plasma‐deposited amorphous silicon

Initial air oxidaton rates and limiting oxide thickness of plasma‐deposited amorphous silicon (a‐Si(H)) films are at least an order of magnitude less than those of single‐crystal silicon. Spectral change resulting from either chemically forced or long–term natural oxidation followed by HF stripping show that oxidation proceeds by consuming inhomogeneously distributed silicon, thereby leading to an increased surface roughness and density deficit in the film.