Incubation Effects upon Polycrystalline Silicon on Glass Deposited by Hot‐Wire CVD

Abstract

A growth mechanism diagnosis for high-rate, polycrystalline silicon deposition using hot-wire CVD is explored in this article. The effects of various deposition parameters on the Si film growth are investigated by Raman spectroscopy and transmission electron microscopy (TEM) measurements, with special attention paid to the crystalline and amorphous phases. It is found that the H 2 /SiH 4 ratio and substrate temperature (T s ) are the essential process parameters in determining the crystalline phase and the incubation thickness of the as-deposited Si film. Under low hydrogen dilution conditions, an amorphous incubation layer was formed and degraded the crystalline fraction of the Si film. The incubation thickness prior to the nucleation decreases with the increase of the hydrogen dilution ratio. Under higher H 2 /SiH 4 ratios (≥50), the amorphous phase deposited on the substrate could be etched selectively by the atomic hydrogen. As a consequence, nucleation of small crystallite occurs directly on the substrate. At low substrate temperatures, the deposition process shows the disadvantages of small grain size and low crystallinity. The poly-Si film can be deposited from the seed layer under high T s conditions (>350°C) where the Si appears singly crystallized at the initial stage and then grows epitaxially.

Carbonized tantalum catalysts for catalytic chemical vapor deposition of silicon films

“…It is shown that crystallinity of the film prepared using carbonized Ta is slightly less than that prepared by uncarbonized Ta at each temperature. As is well known, the crystallinity of Si film usually increases with the thickness during the growth [35,36]. Herein, the less thickness of the film prepared by carbonized Ta catalyst, as will be shown later, is also believed to be responsible for the little less crystallinity.…”

Fabrication and characteristics of porous germanium films

“…The Ge-Ge Raman peak of the top surface layer shifts 5 cm −1 towards lower frequency, whereas the shift is only about 1 cm −1 for the bottom part. Several reasons, such as phonon confinement, stress and polycrystallinity, can shift the Ge-Ge optical phonons [30,31]. Compressive stress leads to an upward shift of the Ge-Ge mode, while a, b, d) and the glass substrate (c).…”

“…As for polycrystallinity, it may result in inhomogeneous broadening (with low frequency tailing) and minor peak shifts [31,36,37]. The effect of stress on Raman shift can be changed by stress relaxation using post-annealing [38][39][40].…”

Simulation and fabrication of heterojunction silicon solar cells from numerical computer and hot‐wire CVD

“…Details of the deposition conditions and properties of all silicon films (n-Si, i-Si and p-Si) were summarized in our earlier report. [24][25][26][27] The solar cell (1 Â 1 cm 2 ) characteristics such as short circuit current density J sc , open circuit voltage V oc , fill factor FF, conversion efficiency h, and external quantum efficiency EQE were measured at 100 mW/cm 2 (AM 1Á5) using a solar simulator.…”

“…Figure 6 shows the dependency of solar cell parameters on the crystallinity of the n-layer and i-layer for the simplest cell structure. The crystallinity of undoped or doped mc-Si films can be controlled by changing the hydrogen dilution, the substrate temperature, and the filament temperature (see our early report 25 ). The solar cells with n-layer/i-layer/c-Si structure were set for simulation in this object.…”