Study of thermal equilibration in selenium- and sulphur-doped a-Si:H

Abstract

The present paper reports the thermal equilibration in selenium-and sulphurdoped hydrogenated amorphous silicon thin films deposited by plasma-enhanced chemical vapour deposition. The conductivity of Se-and S-doped a-Si:H is observed to be very sensitive to the rate at which the samples are cooled following the high temperature anneal. Arrhenius plots of conductivity for various doped films revealed thermal equilibration above the equilibration temperature, T E , thus accounting for larger activation energies. The barrier energy is lower for a-Si,Se:H than for a-Si,S:H, due to a higher defect density in S-doped films.

Optical properties of Se or S-doped hydrogenated amorphous silicon thin films with annealing temperature and dopant concentration

“…A smaller bandgap was observed in the case of the a-Si,Se:H films with a similar gas ratio, this may be because of larger binding energy of the Si-S bond than that of the Si-Se bond [49,50]. The optical absorption measurements show that the incorporation of Se and S into a-Si:H films increases the bandgap of the material and results in increased disorder and higher defect densities [42]. It might be expected that the annealing would remove many of the defects during sample preparation, which are responsible for the performances of the devices [51].…”

“…The optical bandgap of the Se and S-doped a-Si:H films was calculated using Tauc's relation [42,48]:…”

“…The a-Si,Se:H and a-Si,S:H thin films were prepared in an RF plasma glow discharge (13.56 MHz) using plasma enhanced chemical vapor deposition (PECVD) by the decomposition of H2Se and H2S vapors mixed with silane gas (SiH4) on 7059 corning glass at a substrate deposition temperature of 230 • C, respectively [41,42]. The thicknesses of the films measured by a surface profiler (Dektak stylus-Veeco Instruments Inc.) ranged from 0.24 to 5.44 m. The absence of sharp peaks in the X-ray diffraction (XRD Phillips-Holland Diffractometer, model X pert PRO) patterns confirmed the amorphous nature of the films.…”

“…It is documented that prolonged illumination of a-Si:H with bandgap light reduces photoconductivity [16]. It has been suggested that light-induced reduction in photoconductivity may be caused by the creation of metastable recombination centers in the Absorption coefficient, [42]. Hydrogenated amorphous silicon is the basis of an expanding large-area-electronics industry, which started with solar cells for consumer electronic devices and today covers an expanding number of applications, as mentioned above.…”

Progress in electrode and electrolyte materials: path to all-solid-state Li-ion batteries

“…Silicon is the second most abundant element in the earth by mass (25.7%) and very rarely occurs in nature as the pure free element [114]. Silicon is one of the principal components of most semiconductor devices such as integrated circuits (ICs) and microchips [40,41,[115][116][117].…”