研究目的
To investigate the effects of PLD conditions such as laser fluence, ambient pressure, and substrate temperature on the thickness, morphology, and grain size of AlN nano thin films.
研究成果
AlN nano thin films were successfully prepared by PLD. The thickness increases with laser fluence and substrate temperature, grain size increases with laser fluence, ambient pressure, and substrate temperature, and surface roughness increases with these parameters. Preferred orientation growth depends on PLD conditions, with (002) orientation favored at low ambient pressure and (100) at high pressure.
研究不足
The study is limited to specific PLD conditions (laser fluence, ambient pressure, substrate temperature) and may not generalize to other deposition techniques or materials. Potential optimizations include exploring a wider range of parameters or different substrate materials.
1：Experimental Design and Method Selection:
The study used pulsed laser deposition (PLD) to prepare AlN nano thin films on silicon substrates, with systematic variation of laser fluence, ambient pressure, and substrate temperature to analyze their effects. Theoretical models for ablation rate and plasma concentration were referenced.
2：Sample Selection and Data Sources:
Silicon substrates were used, cleaned with HF and distilled water solution, acetone, and ethanol. AlN targets (purity: 99.999%) were prepared from polycrystalline AlN powder sintered in N2 gas.
3：999%) were prepared from polycrystalline AlN powder sintered in N2 gas.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes a KrF excimer laser (Lamda Comprexpro-201, Germany), turbomolecular pump, mass flow controller, UV grade fused quartz lens, X-ray diffractometer (XRD, D8 Discover, Germany), and scanning electron microscope (SEM, Hitachi S-4700 II, Japan). Materials include AlN targets, N2 gas (purity: 99.999%), silicon substrates, HF, acetone, ethanol, and distilled water.
4：999%), silicon substrates, HF, acetone, ethanol, and distilled water.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Substrates were cleaned and loaded into a vacuum chamber evacuated to 6×10^-4 Pa. Substrates were heated to specified temperatures (200, 500, 800°C), N2 pressure was adjusted (5, 10, 100 Pa), and laser ablation was performed with a KrF excimer laser (wavelength: 248 nm, repetition rate: 5 Hz) focused at 45° onto targets. Deposition time was fixed at 90 minutes for all samples.
5：Data Analysis Methods:
XRD was used for phase analysis and grain size calculation using Scherrer's equation. SEM was used for morphology observation and thickness measurement from cross-section images.
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