Effects of RF Power and Substrate Temperature on the Performance of Thin-Film Silicon Solar Cells

Abstract

This article shows the characteristics of pin-type solar cells with different radio frequency (RF) power and substrate temperature (T_s). All films of amorphous materials were deposited by 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) method using a mixture of silane (SiH₄) and hydrogen (H₂). The SiH₄ gas was used as a gas source and the doping process was done by gas admixture of 3% diborane (B₂H₆) diluted in hydrogen (H₂) and 1% phosphine (PH₃) diluted in H₂ for p- and n-layer, respectively. The effects of deposited parameters on the characteristics of a-Si:H films have been investigated by field emission scanning electron microscope (FE-SEM), dark- and photo-conductivity (σ_d and σ_ph) measurement and ultraviolet-visible-near infrared (UV-VIS-NIR) spectrophotometer, respectively. The results showed that the deposition rate of a-Si:H films increased with increasing of RF power and T_s. The optical band gap (E_opt) of a-Si:H films was increased with increasing of RF power from 20–60 Watt, and slightly decreased at RF power of 60–100 Watt. The various values of open-circuit voltage (V_oc), short-circuit current density (J_sc), and conversion efficiency were measured by the solar simulator. It was found that a-Si:H films deposited at RF power of 60 Watt and T_s of 200°C are better suited for thin-film silicon solar cell application.

Keywords:

• a-Si:H
• pin-type solar cell
• optical properties
• electrical properties
• PECVD

Funding

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A2007685), and the Kyungpook National University Research Fund, 2013.