Batch processing method to deposit a-Si:H films by PECVD

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 approximate to 473 K, 60 < pressure 87 Pa, power density of 32 mW/cm(2) and flow of silane approximate to 10 sccm. The growth rate and the microstructure factor are 1.5 Angstrom/s and 3.3 x 10(-2), respectively, while the activation energy approximate to 0.8 eV; dark conductivity at room temperature approximate to 4.37 x 10(-10) (Omegacm)(-1); photosensitivity approximate to 5.02 x 10(6); density of states approximate to 6.6 x 10(15) cm(-3); bonded hydrogen concentration approximate to 20 at% and optical band gap approximate to 1.75 eV.