In this study, TiN-coated cBN (cubic-structure boron nitride) powders were successfully synthesized by a sol-gel method using titanium (IV) isopropoxide (TTIP) and by controlling the heat treatment conditions. After the sol-gel process, amorphous nano-sized TiOx was uniformly coated on the surface of cBN powder particles. The obtained TiOx-coated cBN powders were heated at 1,000~1,300℃ for 1 or 6 h in a flow of 95%N2-5%H2 mixed gas. With increasing temperature, the chemical composition of the TiOx coating layer changed in the order of TiO₂→Ti₆O₁₁→Ti₄O₇→TiN due to reduction of the Ti ions. The TiN coating layer was observable in the samples heated at 1,200℃ and appeared as the main phase in the sample heated at 1,300℃. The resulting thickness of the TiN coating layer of the sample heated at 1,300℃ was approximately 45~50 nm.

Hexagonal boron nitride particles (s-hBN) modified with 3-aminopropyl triethoxysilane (APTES) were used for the preparation of silicone composite materials. The microstructure of the composite materials was observed, and the thermal conduction and mechanical characteristics of the composite sheets were studied based on the compositions and microstructures. When a small amount of s-hBN particles was used, the thermal conductivity of the composite improved as a whole, and the tensile strength of the sheet also increased. The thermal conductivity and tensile strength of the composite in which a small amount of carbon fiber was added along with s-hBN were further improved. However, the use of carbon nanotubes with structural characteristics similar to those of carbon fiber resulted in lower thermal conductivity and tensile strength. Elastic silicone composites exhibiting 2.5 W/mK of thermal conductivity and a low hardness are expected to be used as thermally conductive interfacial sheet materials.

N-type crystalline silicon solar cells have high metal impurity tolerance and higher minority carrier lifetime that increases conversion efficiency. However, junction quality between the boron diffused layer and the n-type substrate is more important for increased efficiency. In this paper, the current status and prospects for boron diffused layers in N-type crystalline silicon solar cell applications are described. Boron diffused layer formation methods (thermal diffusion and co-diffusion using a-SiO_X:B), boron rich layer (BRL) and boron silicate glass (BSG) reactions, and analysis of the effects to improve junction characteristics are discussed. In-situ oxidation is performed to remove the boron rich layer. The oxidation process after diffusion shows a lower B-O peak than before the Oxidation process was changed into SiO₂ phase by FTIR and BRL. The a-SiO_X:B layer is deposited by PECVD using SiH₄, B₂H₆, H₂, CO₂ gases in N-type wafer and annealed by thermal tube furnace for performing the P+ layer. MCLT (minority carrier lifetime) is improved by increasing SiH₄ and B₂H₆. When a-SiO_X:B is removed, the Si-O peak decreases and the B-H peak declines a little, but MCLT is improved by hydrogen passivated inactive boron atoms. In this paper, we focused on the boron emitter for N-type crystalline solar cells.

We investigated and compared two methods of in-situ oxidation and chemical etching treatment (CET) to remove the boron rich layer (BRL). The BRL is generally formed during boron doping process. It has to be controlled in order not to degrade carrier lifetime and reduce electrical properties. A boron emitter is formed using BBr3 liquid source at 930℃. After that, in-situ oxidation was followed by injecting oxygen of 1,000 sccm into the furnace during ramp down step and compared with CET using a mixture of acid solution for a short time. Then, we analyzed passivation effect by depositing Al2O3. The results gave a carrier lifetime of 110.9 ㎲, an open-circuit voltage (Voc) of 635 mV at in-situ oxidation and a carrier lifetime of 188.5 ㎲, an Voc of 650 mV at CET. As a result, CET shows better properties than in-situ oxidation because of removing BRL uniformly.

B-doped Si nanoparticles were synthesized by using inductive coupled plasma and speciallydesigned double tube reactor, and their microstructures were investigated. 0∼10 sccm of B2H6 gas wasinjected during the synthesis of Si nanoparticles from SiH4 gas. Highly crystalline Si nanoparticles weresynthesized, and their crystallinity did not change with increase of B2H6 flow rates. From SEMmeasurement, their particle sizes were approximately 30 nm regardless of B2H6 flow rates. From SIMSanalysis, almost saturation of B in Si nanoparticles was detected only when 1 sccm of B2H6 was injected. When B2H6 flow rate exceeded 5 sccm, higher concentration of B than solubility limit was detected evenif any secondary phase was not detected in XRD or HR-TEM results. Due to their high electronicconductivity, those heavily B-doped Si nanoparticles can be a potential candidate for an active material inLi-ion battery anode.