Optical and structural properties of nanocrystalline silicon potential well structure fabricated by cat-chemical vapor deposition at 200 degrees C.
We attempted to fabricate multi-layer, thin film structures by catalytic chemical vapor deposition (Cat-CVD) at a low temperature (200 degrees C). A 5-10-nm-thick nanocrystalline silicon (nc-Si) layer was positioned asymmetrically between two silicon nitride (SINx) layers. The compositions of the SiNx layers were varied between silicon-rich and nitrogen-rich. Each layer was deposited continuously in the Cat-CVD chamber without post-annealing. High-resolution transmission electron microscopy (HRTEM) revealed that the nc-Si layer grew in columns on the surface of the bottom SiNx layer, and the columnar structure extended up to a few nanometers of the top SiNx layer. In photoluminescence (PL) spectra, the overall intensity increased with the thickness of the nc-Si layer, but the primary peak position changed more sensitively relative to the composition of the SiNx layers. Capacitance-voltage (C-V) hysteresis was observed only when 10-nm-thick nc-Si layers were inserted between the nitrogen-rich silicon nitride (NRSN) layers. Under a bias voltage of 5 V, the current in the sample with a 10-nm-thick nc-Si layer was higher by at least two orders of magnitude than that in the sample with a 5-nm-thick nc-Si layer. The I-V curve was fitted well using both the Fowler-Nordheim and the Poole-Frenkel models for electric fields of magnitudes greater than 1.1 MV/cm, thereby implying that both mechanisms contribute to the increase in the leakage current.
Department of Nano Science and Technology, University of Seoul, Seoul 130-743, Korea.
Sin-Young
SY
Kang
Ki-Su
KS
Keum
Tae-Ho
TH
Song
Wan-Shick
WS
Hong
D002384:Catalysis; D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D005740:Gases / Q000737:chemistry; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012031:Refractometry; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties
D005740:Gases; D046911:Macromolecular Substances; D012825:Silicon