Important role of excited state atoms in low pressure capacitive rf argon discharges

We present the important role of realistic electron-induced secondary electron emission (SEE) [Vaughan, IEEE Trans. Electron Devices 40, 830 (1993)], metastable atom and photon-induced secondary electrons from electrodes on the plasma density in low pressure capacitive argon discharge at 13.56MHz. With the above three kinds of secondary electron emission included in the particle-in-cell (PIC) simulations, the plasma density shows good agreement with that from recent experiments [Schulenberg et al Plasma Sources Sci. Technol. 30 (2021) 105003] at low pressure (1-10 Pa). At 20Pa, the plasma densities in PIC simulation are higher than the experiments for 250 and 350V, which is the subject of further investigation. The mechanism of plasma density enhancement due to secondary electron emission will also be discussed in detail.