Can RF Sputtering cause the the ejected target to ionise?

In summary, the conversation discusses the use of sputtering method for thin film deposition of III-Nitrides using a GaN target and RF plasma generation. After conducting phase analysis, it was found that Ga2O3 was deposited and crystalline in nature. The explanation for this is that the GaN molecules are dislodged by energy transfer from Ar ions and then broken in the RF region, allowing Ga and N ions to be deposited on the surface. However, there is a question about the plausibility of the neutral Ga-N bond being broken in the RF region. The bonding strength of GaN and Ar is compared, and it is suggested to determine the energy given by the RF radiation to further understand this process.
  • #1
maxxlr8
12
0
Hello,

I am currently working on sputtering method for thin film deposition of III-Nitrides. The target used was a gallium nitride (GaN) plate and plasma generation was achieved by radio frequency (RF).

After running the sample through phase analysis, interestingly a gallium oxide (Ga2O3) peak has been observed, indicating that not only Ga2O3 has been deposited, but it is also crystalline in nature.

My only explanation is as follows
  1. After being bombarded by the argon (Ar) ions, the GaN molecules will be dislodged by energy transfer and move away to the substrate.
  2. While passing the area with RF radiation, the Ga-N bond breaks, leaving Ga and N ions to be deposited on the surface.
  3. Due to the residual oxygen (O) inside the growth chamber at low vacuum, the N and O will face competition to be adsorbed to the Ga dangling bond
  4. Therefore, Ga2O3 can be formed

Is this plausible? Can the neutral Ga-N bond that is passing in the RF region somehow get broken? I am saying this because since the RF is energetic enough to ionise an inert gas (Ar), it could also could break a covalent bond of GaN.

Pardon me if I got the facts wrong.

Thank you for reading this.
 
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  • #2
You should double check this by figuring out the bonding strength of GaN.

Zz.
 
  • #3
ZapperZ said:
You should double check this by figuring out the bonding strength of GaN.

Zz.

The bonding strength of Ga-N is 8.92 ev/atom [1],
Whereas the bonding strength of Ar is 4.73 kJ/mol [2]. Converting this, I got ~0.049 eV/atom.

It can be seen that Ga to N bonding has a higher bonding strength compared to Ar. However, in my opinion, I should determine the energy given by the RF radiation. Is this the right track?

Reference
[1] W. A. Harrison, Electronic Structure and Properties of Solids, Freeman, San Francisco, (1980)
[2] http://www.webelements.com/argon/bond_enthalpies.html
 
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1. Can RF Sputtering cause the ejected target to ionise?

Yes, RF sputtering can cause the ejected target to ionise. When a target material is bombarded with high-energy ions from the RF plasma, it can lead to the emission of electrons from the target surface, resulting in the ionisation of the ejected particles.

2. How does RF Sputtering cause ionisation of the ejected target?

RF sputtering causes ionisation of the ejected target through a process called sputtering. When high-energy ions from the RF plasma collide with the target material, they can knock out electrons from the target surface, creating positively charged ions. These ions can then be accelerated by the electric field of the plasma, leading to the ionisation of the ejected particles.

3. What factors affect the degree of ionisation in RF Sputtering?

There are several factors that can affect the degree of ionisation in RF sputtering, including the power and frequency of the RF source, the composition and pressure of the gas used, and the properties of the target material. Increasing the power and frequency of the RF source can lead to more energetic ions, resulting in a higher degree of ionisation. Using a gas with a higher atomic mass can also enhance the ionisation process.

4. Can the degree of ionisation be controlled in RF Sputtering?

Yes, the degree of ionisation in RF sputtering can be controlled by adjusting the process parameters mentioned above. By optimizing the RF power and frequency, gas composition and pressure, and target material properties, it is possible to achieve a desired degree of ionisation in the ejected target particles.

5. What are the applications of ionisation in RF Sputtering?

The ionisation of ejected target particles in RF sputtering has several applications, including thin film deposition, surface modification, and thin film analysis. By controlling the degree of ionisation, it is possible to tailor the properties of the deposited thin film, such as composition, structure, and morphology. Ionisation can also enhance the adhesion of thin films to the substrate and improve their mechanical and electrical properties.

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