In situ observation of nucleation and subsequent growth of clusters in silane radio frequency discharges

Abstract

Growth processes of clusters in low-pressure and low-power silane radio frequency discharges are studied by using the newly developed double-pulse-discharge method which realizes in situ measurement of their size and density in a size range of 0.5–4 nm. The clusters begin to be composed of two size groups at about 10 ms after the discharge initiation: clusters in the small size group have an almost constant average size of about 0.5 nm through the discharge period, while those in the large one grow at about 4 nm/s in a monodisperse way. Time evolution of the measured average sizes and densities in the groups is transformed into that of size distributions assuming that the density of SinHx clusters for the small group decreases exponentially with the increase in the number of Si atoms, n, of them, and the size distribution for the large group is the lognormal one. The results show that a critical cluster size for nucleation is SinHx (n∼4).

New approaches for the production of nano‐, micro‐, and polycrystalline silicon thin films

“…Indeed, the Raman spectrum can be simulated with two Gaussian bands located at 501 and 515 cm How to explain the obtaining of such a high crystalline fraction? Because the plasma is at a pressure (700 mTorr) below the onset of agglomeration [20], we can estimate that the density of nanocrystals is in the range of 10 10 cm -3 [75,76], i.e., of the same order of magnitude of the density of silicon radicals. Thus we can argue that the film is fully crystallized because the contribution of radicals is negligible compared to the contribution of nanocrystals.…”

Deposition of cluster‐free P‐doped a‐Si:H films using SiH4+PH3 multi‐hollow discharge plasma CVD

“…Light-induced degradation is an important issue in a-Si:H films because light exposure initially causes a reduction of the conversion efficiency of the cells due to degradation [2,3]. During the deposition, amorphous silicon particles (clusters) smaller than 10 nm are generated in plasmas, and can be deposited into films [4][5][6]. Lower volume fraction of clusters in films shows lower concentration of Si-H 2 bonds in films [7], which are responsible for lightinduced degradation of the films [8].…”

Formation of carbon nanoparticle using Ar+CH4high pressure nanosecond discharges

“…For instance, surface modification of Si nanoparticles has been realized using twin plasmas [6]. Formation kinetics of nanoparticles in low pressure non-thermal plasmas and in high pressure thermal plasmas and their applications have been extensively studied [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], while nanoparticle synthesis using high pressure non-thermal plasmas has been attracted relatively little attention. For the high pressure thermal plasmas such as arc plasmas, a large amount of radicals are produced by high density plasmas at high gas pressure and hence productivity of nanoparticles is high.…”