Study of nanocrystalline silicon films synthesized below 100 °C by catalytic chemical vapor deposition

Nanocrystalline silicon (nc-Si) films were synthesized by catalytic chemical vapor deposition at a low substrate temperature (100 °C) for use as an active layer in bottom-gate thin-film transistors. The hydrogen-dilution technique was employed to increase the crystalline volume fraction of the synthesized films. The incubation layer thickness was estimated to be 5.1 nm for a hydrogendilution ratio, R_H (= [H₂]/[SiH₄]), of 54. When R_H was increased from 64 to 74, the deposition rate decreased from 20 to 0.5 nm/min. In order to achieve a high deposition rate and high crystallinity near the interface region, we modulated R_H through the film thickness. We also fabricated metal-insulator-semiconductor-insulator- semiconductor diodes from multilayer structures consisting of an nc-Si layer sandwiched between two silicon nitride layers. By analyzing the capacitance-voltage characteristics of these diodes, we found that the hysteresis and rectifying behavior of these diodes were affected by the the nc-Si layer thickness.