Fabrication of p-type SnOx films and research into the effects of Na impurities on their optical, electrical, and structural characteristics for use in the development of optoelectronics.

Theoretical results:
- It has been demonstrated through the study method that doping Na into the SnOx film can boost the hole conductivity of the p-type SnOx semiconductor.
- In this report, Na doping percentage of 3 at% in Sn+Na alloy targets would result in 1.56 at% of Na in prepared films. These samples presented the best electrical properties of SnOx:Na films ( nh =2.75x1019cm-3, μ = 2.4 cm2/VS, ρ = 9.35x10-2Ωcm)
- After sputtering, the annealing temperature was investigated. It was discovered that while the film exhibited a p-type SnO structure at 300 0C, there was a phase change from SnO crystal to amorphous phase from 300 0C to 400 0C. When the annealing temperature is raised from 400 °C to 500 °C, the amorphous phase transforms into the intermediate phase Sn2O3, Sn3O4, and from the phase Sn2O3, Sn3O4 to the SnO2 phase when the temperature is raised from 550 °C to 600 °C.
- As the sputtering duration lengthens, the film thickness also lengthens, which increases the carrier concentration and mobility and causes a dramatic decrease in the film's resistivity.It is unnecessary to keep extending the sputtering period because doing so results in a large reduction in the SnOx:Na film's resistivity, transmittance, and band gap energy.Therefore, the sputtering period in the SnOx:Na film formation process by reactive sputtering was chosen in the range of 14 minutes to 21 minutes in order to balance the electrical and optical properties.
Applied results: Fabrication of diode based on p-n heterojunction between n-nc-Si:H and p-SnOx:Na as a topic for applications in manufacturing photovoltaic components such as photodiodes, solar cells, transistors...

- The melting and casting technique was used to create the Sn + Na alloy sputtering target.
- Fabrication of Na-doped p-SnOx-type semiconductor film with high hole concentration, mobility, and conductivity, meeting application requirements in semiconductor devices.

- Scientific papers in referred journals (list):
+ An article titled "Effect of sodium doping on properties of p-SnOx films produced by reactive direct current magnetron sputtering" appeared in the esteemed Ceramics International journal, with an IF of 5,532 and a Q1 quality index.
+ An article titled "Effect of sputtering time on characteristics of p-SnOx:Na films prepared by reactive direct current magnetron sputtering" was published in the journal Science and Technology Development, Vietnam National University, Ho Chi Minh City.