[11p-Z01-1~11] 13.2 Exploratory Materials, Physical Properties, Devices

▲ [11p-Z01-3] Optical properties improvement of lightly and heavily boron-doped BaSi₂ by atomic H passivation

〇(D)Zhihao Xu¹, Kaoru Toko¹, Takashi Suemasu¹ (1.Univ. Tsukuba)

Keywords:H passivation

Semiconducting BaSi₂ has many advantages for solar cell applications, such as a suitable band gap of 1.3 eV, a large absorption coefficient of 3 × 10⁴ cm^-1 at 1.5 eV, and a large minority-carrier diffusion length of ca. 10 μm [1]. The first-principle calculation predicts Si vacancies to be most likely to occur as point defects in BaSi₂ regardless of Si-rich or Si poor growth conditions and lead to the degradation of the minority-carrier properties of BaSi₂[2]. Therefore, we try to passivate defects in undoped BaSi₂ films by atomic hydrogen (H). The photoresponsivity of undoped BaSi₂ films is enhanced markedly by irradiation of atomic H after the growth of BaSi₂ films for 15 min thanks to the improvement of minority carrier lifetime [3]. The basic solar cell structure is pn junction. Thus, the passivation of impurity-doped p- or n-BaSi₂ films is of particular importance. In this study, we investigate the effect of atomic H passivation on the photoresponsivity property of lightly (p = 7 × 10¹⁶ cm^-3) and heavily (p = 3 × 10¹⁸ cm^-3) boron (B) -doped p-BaSi₂.