• Pereira, Luis
• Águas, Hugo
• Ferreira, Isabel
• Martins, Rodrigo
• Raniero, L.

Abstract

<p>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 &lt;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.</p>

Topics

• Deposition
• density
• impedance spectroscopy
• microstructure
• surface
• amorphous
• Hydrogen
• Silicon
• activation