STRUCTURAL AND ELECTRICAL-PROPERTIES OF THIN MICROCRYSTALLINE SILICONFILMS DEPOSITED BY AN ELECTRON-CYCLOTRON-RESONANCE PLASMA DISCHARGE OF 2-PERCENT SIH4 AR FURTHER DILUTED IN H-2/

Microcrystalline silicon (mu c-Si) was deposited in a simple, low cost microwave electron cyclotron resonance plasma system by H-2 dilution of 2% SiH4/Ar. The film growth and properties have been examined with substrate temperatures between 300 and 450 degrees C for pressures of 1-40 mTorr. Raman spectroscopy has been used extensively to study the microstructure of the film, and to determine the crystallized fraction and grain sizes in the film, for growth variations caused by H-2 dilu tion, growth pressure, and temperature. H-2 dilution of the plasma is found to increase the grain size and the crystallized fraction of the deposited films. Crystallization could also be initiated in the films deposited using only the Ar diluted SiH4 by increasing the power coupl ed to the discharge. Increasing the H-2 dilution results in compact fi lms with a low hydrogen content, while a decrease is seen to create mo re voids in the film. The mu c-Si films (similar to 70% crystallized f raction), prepared at 400 degrees C, with grain sizes between 200 and 300 Angstrom, exhibit a low dark conductivity of 3 x 10(-6) S/cm with conduction activation energies between 0.3 and 0.43 eV. The structural properties of the film, evaluated by Raman spectroscopy and evolved g as analysis, are correlated with the dark/ photoconductivity observed in the film. The experimental data suggest etching by atomic hydrogen to be the primary mechanism responsible for the crystallization of the films. (C) 1998 American Vacuum Society. [S0734-2101(98)01005-7].