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Published on: November 9, 2015
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Surface Morphology and Structural Modification Induced by Femtosecond Pulses in Hydrogenated Amorphous Silicon Films
Journal of Nanoscience and Nanotechnology
|September 29, 2015
Summary
Femtosecond laser irradiation modifies hydrogenated amorphous silicon (a-Si:H) films, creating surface spikes and influencing nanocrystal formation. Optimizing laser parameters is crucial for device development due to trade-offs in structure and morphology.
Area of Science:
- Materials Science
- Nanotechnology
- Laser Physics
Background:
- Hydrogenated amorphous silicon (a-Si:H) is a key material in semiconductor devices.
- Laser irradiation offers a method for modifying thin film properties.
Purpose of the Study:
- To investigate the structural and morphological changes in a-Si:H thin films induced by femtosecond laser irradiation.
- To analyze the relationship between laser fluence and the resulting surface morphology and crystalline structure.
Main Methods:
- Femtosecond laser irradiation (150 fs, 775 nm, 1 kHz) was applied to a-Si:H thin films.
- Atomic Force Microscopy (AFM) with specialized software was used for statistical analysis of surface morphology (spikes).
- Raman spectroscopy was employed to determine the crystalline fraction and crystal size.
Main Results:
- Laser irradiation at 3.1 MJ/m² resulted in spikes with an average height of ~15 nm.
- Higher fluences (> 3.7 MJ/m²) led to spike aggregation and increased crystalline fraction (up to 73%).
- Increased fluence also caused a decrease in nanocrystal size.
Conclusions:
- A trade-off exists between spike distribution, crystallization fraction, and nanocrystal size.
- Laser irradiation parameters must be carefully controlled for effective device development using modified a-Si:H films.
