Yoshihiko Kusakabe

Rear-emitter Si heterojunction solar cells with over 23% efficiency

We have developed highly crystallized n-type microcrystalline Si layers as window layers for rear emitter Si heterojunction solar cells. We introduce a seed layer between an n-type microcrystalline Si layer and an intrinsic amorphous Si layer to improve the crystallinity of the n-type microcrystalline Si layer. By using this stacked layer instead of an n-type amorphous Si layer, the contact resistance between the n-type thin layer and In2O3:H is reduced without Al-doped ZnO. As a result, we obtain a high short-circuit current and a high fill factor simultaneously, and achieve a solar cell efficiency of 23.43%.

Preparation and Characterization of Superconducting Y–Ba–Cu–O Films by the MOCVD Technique

Superconducting Y–Ba–Cu–O thin films were obtained by the MOCVD technique on MgO(100) substrates at 715°C without postannealing. β-diketonate chelates were used as source metal organic complexes. This paper describes the film characterizations of electrical resistivity, composition, surface morphology and microstructure. Superconducting films were composed of a dense matrix and dispersed particles. The Y–Ba–Cu composition of the matrix was close to the 1:2:3 superconducting phase, while the particles were mainly composed of CuO. The highest zero-resistant temperature obtained in this experiment was 85 K. The film was highly oriented with the c-axis normal to the substrate. The lattice constant of the film was 11.68 A.

Preparation of Nearly Stoichiometric Superconducting Y-Ba-Cu-O Films by an MOCVD Technique Using Ozone

Superconducting Y-Ba-Cu-O films of nearly stoichiometric composition (Y:Ba:Cu=1:2:3.6) were prepared by an MOCVD technique on MgO(100) substrates at 650°C without postannealing. By introducing ozone into the reactor, we obtained a film with higher zero resistive temperature (75 K) and better surface morphology and c-axis orientation, compared to a film of the same composition prepared without ozone.

Investigation of Precursors Formed by Mixing SiH2Cl2 with NH3 for Chemical Vapor Deposition of Silicon nitride Films

Precursors for Silicon nitride films prepared by mixing SiH2Cl2 with NH3 were investigated by in situ Fourier-transform infrared spectroscopy (FT-IR) and mass spectrometry. The FT-IR spectral analysis results indicated that the Cl was removed from SiH2Cl2 by mixing SiH2Cl2 with NH3 at room temperature (R.T.). The analysis results also indicated the existence of radicals which had the chemical bond Si–N. The mass spectral analysis results indicated the existence of the radicals with the mass number of 45–47. From these results, it was concluded that the precursors of SiNHx for SiN films were formed by mixing SiH2Cl2 with NH3.

Conformal deposition on a deep-trenched substrate by MOCVD

Abstract An improvement in step coverage of metal films deposited over deep trenches was studied. When sufficient source gas with low sticking probability was uniformly supplied to all surface of trenches without any source decomposition, successful conformal deposition of metal films was achieved over trenches with high-aspect ratios of up to 4.

Preparation of Y-Ba-Cu-O Superconducting Films by MOCVD Using Ozone

As-grown superconducting Y-Ba-Cu-O films were prepared by an MOCVD technique at the substrate temperature below 650°C. As precursors, s-diketonate complexes were used, and oxygen including ozone was used for oxidation. The highest zero-resistive temperatures (Tc) were 84K and 74K prepared at 650°C and 620°C, respectively. The films with Tc of 61K were prepared at 620°C, in the nearly stoichiometric composition (Y:Ba:Cu=1:2:3). On the other hand, no zero-resistivity was observed in the films prepared at 580°C. The substrate temperature of about 600°C was the lower threshold to get zero-resistivity in this experiment.