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This work reports a technique to obtain electronic grade intrinsic amorphous silicon using the plasma enhanced chemical vapour deposition technique at 13.56 MHz. The batch processing method consists of igniting the plasma process through a neutral gas such as hydrogen or helium and only feeding the carrier gas containing the species to be decomposed into the reactor when the plasma is stabilized. By doing so, no surface damage is induced in the first deposited layers and so a more compacted and stable film is produced, compared to amorphous films grown by conventional methods. The best deposition conditions to produce films with good transport properties for optoelectronic applications are: temperature ≈ 473 K, 60 < pressure 87 Pa, power density of 32 mW/cm2 and flow of silane ≈ 10 sccm. The growth rate and the microstructure factor are 1.5 Å/s and 3.3×10-2, respectively, while the activation energy ≈ 0.8 eV; dark conductivity at room temperature ≈ 4.37×10-10 (ωcm)-1; photosensiti-vity ≈ 5.02×l06; density of states ≈ 6.6×1015 cm-3; bonded hydrogen concentration ≈ 20 at% and optical band gap ≈ 1.75 eV.

The aim of this paper is to compare the density of bulk states (DOS) of polymorphous silicon (pm-Si:H) films produced by plasma enhanced chemical vapor deposition at 13.56 and 27.12 MHz using the constant photocurrent method and the space charge limited current (SCLC) technique. The data achieved revealed that the set of films produced present similar DOS. Apart from that, data concerning the correlation of the deposition conditions that lead to the production of pm-Si:H as well as their characteristics, such as the hydrogen content and how hydrogen is bonded, will be discussed, giving special emphasis to the set of mechanical stresses developed. By doing so we could get a better understanding of the nature of hydrogen bonding in pm-Si:H films as well as to determine the role of the excitation frequency on the film's performances, where films with amounts of hydrogen around 20 at.% can have DOS as low as 8 × 10 14 cm-3 with Urbach energies in the range of 41-50 meV. © 2004 Elsevier B.V. All rights reserved.