Laser crystallization of hydrogenated amorphous silicon

Abstract

Doped and undoped hydrogenated amorphous silicon films were crystallized employing a step-by-step laser crystallization method. The influence of laser crystallization on structural properties and hydrogen bonding in polycrystalline silicon was investigated using Raman backscattering spectrometry, electron paramagnetic resonance, and hydrogen effusion measurements. At low laser fluences, E L , a two-layer system is created. With increasing E L the spin density of undoped poly-Si increase and saturates at a value of about 5.2×1018 cm -3 . With increasing boron and phosphorous concentration the LO-TO phonon line shifts to smaller wave numbers and broadens asymmetrically due to a resonant interaction between optical phonons and direct intraband transitions known as a Fano resonance. From H effusion spectra the hydrogen density-of-states distribution is derived. Laser crystallization results in an increase of the H bonding energy by about 0.3 eV. Interestingly, H bonding is also affected by the deposition temperature of the amorphous starting material. In completely crystallized poly-Si a residual H concentration of up to 17 at.% can be observed.

Determining the content and binding energy of hydrogen in diamond films

“…Apparently, studies of this kind always seem to involve a need to determine the content of hydrogen and its binding energies in the structures under study. At present, the content of hydrogen in films is commonly determined by indirect methods [9].…”

Determining the bound energies of dissolved hydrogen on the basis of a multichannel diffusion model in a solid

“…When the sample is heated, the temperature of the adjacent parts of the extraction system is growing. In some cases, the magnitude of the background hydrogen flow increases by a factor of hundreds during TDS measurements [15] . It is quite common for the TDS method to pre-saturate the samples with hydrogen, which allows to reduce the effect of the growing background flows.…”

“…The vacuum-heating method [15][16][17][18] is one of the ways for measuring hydrogen concentrations in solid samples; it is used in research as well as in the industrial monitoring. For our experiments we used an industrial AB-1 hydrogen analyzer with massspectrometric monitoring of the time dependence of hydrogen flow from a sample heated in vacuum.…”

“…It is possible to estimate the binding energies through using other methods, for example, the spectral method [15] , but this only works well for thin samples in the form of films and membranes.…”

Calculating the activation energies of nickel, manufactured using 3D printing technology, with multichannel hydrogen diffusion model

“…This effect is usually not discussed, however, research shows, that the growth of the background flows can significantly impact the results of the measurements with a constant increase in temperature of a studied sample cf. [24,29,30].…”