[23a-P07-1~3] 16.1 Fundamental properties, evaluation, process and devices in disordered materials

[23a-P07-2] Substrate potential dependence of optical characteristics of a-Si: H for shortwave near-infrared filter by DC and RF sputtering

〇Yoshio Kawamata¹, Hiroshi Ito¹, Hiroyuki Nikkuni¹, Mikio Ito¹ (1.National inst, of Tech.Toko college)

Keywords:a-Si:H, Band pass Filter, Substrate potential

In recent years, there has been a demand for the using of hydrogenated amorphous silicon (a-Si: H), which is inexpensive and is high refractive index and is highly compatible with devices, to an optical laminated filter for near-infrared wavelength. The CVD method is generally used for a-Si: H, which has been put into practical use in solar cell applications, and plasma damage is an issue in the case of sputter deposition. On the other hand, there are few research reports on plasma damage to a-Si: H for optical film applications. Therefore, we investigated the relationship between the substrate potential which affect the bombardment of charged particles on the substrate during reactive sputtering, and the film structure, and the optical properties. As the negative potential of the substrate increased, the surface roughness Ra of the film decreased. While the Si-H2 bond ratio (Si-H2 / Si-H) increased and the refractive index Nf decreased. Similar to general bias sputtering, the surface morphology was smoothed by ion bombardment. However, it is considered that the Si-H2 bonds were increased due to breaking of Si-Si bonds and, so that the film structure becomes a fine structure containing voids, and as a result, Nf decreased. The day of the presentation, we will also report the evaluation results of thermal durability and BPF.