結晶SeフォトダイオードのパターニングのためのTe下地層の検討

抄録

Selenium is one of the promising materials for optical absorbers of photovoltaic conversion under room lighting conditions. According to the bandgap energy of selenium (E_g = 1.91 eV), selenium thin film photodiode exhibits high sensitivity at visible wavelengths. We developed the patterning process of selenium photodiode. The adhesion strength of selenium is an important factor to fabricate micro photodiodes. While insertion of a very thin tellurium layer below the selenium layer increases adhesion strength between the selenium layer and the substrate, however the excessive addition of tellurium increases dark current by increasing carrier densities of selenium layer. This paper investigates the influences of insertion of a variety of tellurium underlying layer on material properties of selenium optical absorber layer, such as optical properties, crystallinity and mechanical characteristics. In conclusion, it is suggested that adding thicker tellurium increased adhesion strength between a selenium layer and a substrate. On the other hands, the excessive thickness of tellurium (> 0.9 nm) deteriorated crystallinity of selenium and increased both dark current and undesirable photogenerated current at infrared wavelengths.