Satoshi Tohoda

A new record conversion efficiency of 24.7% was attained at the research level by using a heterojunction with intrinsic thin-layer structure of practical size (101.8 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , total area) at a 98-μm thickness. This is a world height record for any crystalline silicon-based solar cell of practical size (100 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and above). Since we announced our former record of 23.7%, we have continued to reduce recombination losses at the hetero interface between a-Si and c-Si along with cutting down resistive losses by improving the silver paste with lower resistivity and optimization of the thicknesses in a-Si layers. Using a new technology that enables the formation of a-Si layer of even higher quality on the c-Si substrate, while limiting damage to the surface of the substrate, the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> has been improved from 0.745 to 0.750 V. We also succeeded in improving the fill factor from 0.809 to 0.832.

The magnetic anisotropy of monatomic Fe films on Pd(001) with or without a Pd overlayer was investigated from the standpoint of interface atomic structures. Quantitative analysis included low-energy electron diffraction and x-ray magnetic circular dichroism (XMCD) experiments, and first-principles calculations were also performed on monatomic Fe and Pd/Fe systems. It was revealed that Fe atoms intermix with the Pd substrate at room temperature. A spin reorientation transition occurs at a critical Fe thickness of 1.2 monolayers (ML) in Fe/Pd(001), while in-plane magnetic anisotropy is persistent in Pd/Fe/Pd(001) throughout the entire sample. The Fe 3$d$ spin and orbital magnetic moments for both systems are strongly enhanced near 1 ML Fe thickness, as compared to those of the bulk iron crystal. In addition, an induced magnetic moment in interfacial Pd atoms was observed by XMCD at the Pd ${M}_{2,3}$ core absorption edges. It was concluded that the $L{1}_{0}$-like tetragonally distorted interface atomic structure in monatomic Fe/Pd(001) induces the perpendicular magnetic anisotropy.

We investigated the magnetic anisotropy of bare and Pd-capped Fe ultra-thin films on the Pd(001) single crystal substrate using soft X-ray magnetic circular dichroism (XMCD) spectroscopy. XMCD spectra indicate that the spin reorientation transition (SRT) occurs in Fe/Pd(001). It is suggested that the SRT in Fe/Pd(001) is related to the film morphology. In Pd/Fe/Pd(001), in-plane magnetic anisotropy was observed. No evidence of perpendicular magnetic anisotropy was obtained, which is in contrast to the L10-ordered FePd alloy. [DOI: 10.1380/ejssnt.2008.246]

We hereby report a growth mode and surface structure of ultrathin Cr films on fcc Fe/Cu(001). We have found a clear RHEED intensity oscillation during Cr deposition up to four monolayers on 3 and 6 ML Fe/Cu(001), indicating an layer-by-layer growth. Besides, the observed (2×1) LEED pattern at low Cr thickness is similar to that of fcc Fe/Cu(001) in the 5-11 ML thickness range. We have also demonstrated the Cr/Fe multilayer growth with single monolayer of Cr inserted between fcc Fe layers. [DOI: 10.1380/ejssnt.2008.251]