13:30 〜 15:30
▲ [7p-PB4-10] Carrier transport properties of boron-doped p-BaSi2 on Si(111) and Si(001)
キーワード：barium disilicide, carrier transport
Barium disilicide (BaSi2) has attractive features for solar cell application such as a suitable band gap, a large minority-carrier lifetime (τ ~ 10 μs) and a large minority-carrier diffusion length (L ~ 10 μm). In our previous work, we successfully grew boron (B)-doped p-BaSi2 on a flat n-Si(111) substrate to form pn junction solar cells and achieved an efficiency of 9.9%. However, the carrier transport properties of B-doped p-BaSi2 have not been investigated. In this study, we attempted to explore the carrier transport properties of B-doped p-BaSi2 on Si(111) and Si(001). They are both a-axis-oriented multi-domain epitaxial layers; there are three and two epitaxial variants rotating by 120 and 90 deg with each other around the surface normal, respectively. Furthermore, the potential profiles across the grain boundaries in undoped n-BaSi2 differ between them. Hence, the scattering mechanisms in those films are of great importance when we apply these materials to solar cells.
We used FZ-n-Si(111) and FZ-n-Si(001) substrates with high-resistivity of more than 1000 W×cm. B-doped p-BaSi2 epitaxial films exceeding 400 nm in thickness were grown by molecular beam epitaxy (MBE) using reactive deposition epitaxy templates. The temperatures of B K cell (TB) were set at 1000, 1100, 1170, 1230 and 1300 °C. Then, a 3-nm-thick a-Si layer was prepared over the BaSi2 layers as a capping layer to reduce oxidation of the film. The mobility μ was measured at temperatures between 30 and 300 K using the Van der Pauw method. The applied magnetic field was 0.3T normal to the sample surface.
We used FZ-n-Si(111) and FZ-n-Si(001) substrates with high-resistivity of more than 1000 W×cm. B-doped p-BaSi2 epitaxial films exceeding 400 nm in thickness were grown by molecular beam epitaxy (MBE) using reactive deposition epitaxy templates. The temperatures of B K cell (TB) were set at 1000, 1100, 1170, 1230 and 1300 °C. Then, a 3-nm-thick a-Si layer was prepared over the BaSi2 layers as a capping layer to reduce oxidation of the film. The mobility μ was measured at temperatures between 30 and 300 K using the Van der Pauw method. The applied magnetic field was 0.3T normal to the sample surface.