In this paper, we investigated the effect of the passivation stack with Al2O3, hydrogenated silicon nitride (SiNx:H) stack and Al2O3, silicon oxynitride (SiONx) stack in the n type bifacial solar cell on monocrystalline silicon. SiNx:H and SiONx films were deposited by plasma enhanced chemical vapor deposition on the Al2O3 thin film deposited by thermal atomic layer deposition. We focus on passivation properties of the two stack structure after laser ablation process in order to improve bifaciality of the cell. Our results showed SiNx:H with Al2O3 stack is 10 mV higher in implied open circuit voltage and 60 μs higher in minority carrier lifetime than SiONx with Al2O3 stack at Ni silicide formation temperature for 1.8% open area ratio. This can be explained by hydrogen passivation at the Al2O3/Si interface and Al2O3 layer of laser damaged area during annealing.

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide(Cu2O) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of Cu2O is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of Cu2O while imperfections of the Cu2O thin films are removed. This study investigates the photoelectrochemical properties of Cu2O. However, severe photo-induced corrosion impedes the use of Cu2O as a photoelectrode. Two candidates, TiO2 and SnO2, are selected for the passivation layer on Cu2O by by considering the Pourbaix-diagram. TiO2 and SnO2 passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that SnO2 is a good passivation layer for Cu2O.

본 연구에서는 용액 공정으로 제작된 단분자 기반의 유기 반도체 전계효과 트랜지스터에 적용된 보호막이 유기 트랜지스터의 전기적 안정성에 미치는 영향에 대해여 살펴보았다. Solvay社에서 제공한 용액 공정형 유기 단분자 반도 체를 채널로 사용하여 제작한 유기 트랜지스터는 약 1 cm2/Vs의 상대적으로 높은 이동도를 보였으며, 대략 2.5 ~ 20 k Ωcm 범위의 낮은 접촉저항을 가진 것으로 측정되었다. 무엇보다 중요한 것은, 제작한 유기 트랜지스터에 불소원자가 함유된 Hyflon AD를 보호막으로 적용하였을 때, 보호막을 적용하기 전에 비해 훨씬 더 향상된 전기적 안정성을 보였 다. 이는 불소원자가 함유된 Hyflon AD 고분자막이 대기 중의 수분을 효과적으로 차단하기 때문으로 추측된다.

During sintering of Ni-electrode multi-layer ceramic capacitors (MLCCs), the Ni electrode often becomes discontinuous because of its lower sintering temperature relative to that of BaTiO3. In an attempt to retard the sintering of Ni, we introduced passivation of the Ni powder. To find the optimal passivation conditions, a thermogravimetric analysis (TGA) was conducted in air. After passivation at 250oC for 11 h in air, a nickel oxide shell with a thickness of 4- 5 nm was formed on nickel nanoparticles of 180 nm size. As anticipated, densification of the compacts of the passivated Ni/NiO core-shell powder was retarded: the starting temperature of densification increased from ~400oC to ~600oC in a 97N2-3H2 (vol %) atmosphere. Grain growth was also retarded during sintering at temperatures of 750 and 1000oC. When the sintering atmosphere was changed from wet 99.93N2-0.07H2 to wet 99.98N2-0.02H2, the average grain size decreased at the same sintering temperature. The conductivity of the passivated powder sample sintered at 1150oC for 8 h in wet 99.93N2-0.07H2 was measured to be 3.9 × 104 S/cm, which is comparable with that, 4.6 × 104 S/ cm, of the Ni powder compact without passivation. These results demonstrate that passivation of Ni is a viable means of retarding sintering of a Ni electrode and hence improving its continuity in the fabrication of BaTiO3-based multi-layer ceramic capacitors.

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafers. It is observed that the passivation quality of a-Si:H thin-films on c-Si wafers depends highly on the initial H-termination properties of the wafer surface. The effective minority carrier lifetime (MCLT) of highly H-terminated wafer is beneficial for obtaining high quality passivation of a-Si:H/c-Si. The wafers passivated by p(n)-doped a-Si:H layers have low MCLT regardless of the initial H-termination quality. On the other hand, the MCLT of wafers incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with initial cleaning and H-termination schemes. By applying the improved cleaning processes, we can obtain an MCLT of 100μsec after H-termination and above 600μsec after i a-Si:H thin film deposition. By adapting improved cleaning processes and by improving passivation and doped layers, we can fabricate a-Si:H/c-Si heterojunction solar cells with an active area conversion efficiency of 18.42%, which cells have an open circuit voltage of 0.670V, short circuit current of 37.31 mA/cm2 and fill factor of 0.7374. These cells show more than 20% pseudo efficiency measured by Suns-Voc with an elimination of series resistance.

HBr을 이용한 트렌치 식각시 식각 방지막의 형성과 이들이 결함 생성 및 분포에 미치는 영향을 고분해능 투과전자현미경을 이용하여 연구하였다. O2 및 다른 첨가 가스로 SiOxFy, SiOxBry 등의 식각 방지막을 표면에 형성시켜 벽면 undercut을 방지하고 표면의 거칠기를 감소할 수 있었으며, 이후의 트렌치 채움 공정에서 void 가 없는 잘 채원진 구조를 얻을 수 있었다. 형성된 식각 방지막은 격자 결함의 생성 및 이들의 분포에 영향을 미쳤다. 대부분의 식각 유도 결함들은 트렌치 바닥의 가장자리에서 10Å 이내의 깊이로 분포하였으며, 잔류막의 두께에 의존하였다. 두꺼운 잔류막층 아래로는 결함들이 거의 사라졌으며, 결함층의 깊이와 잔류막 두께는 대체로 반비례하는 것을 나타났다. 기판 내에 존재하는 결정학적인 결함들은 식각종의 입사각이나 에너지에 의존하는 반면에,식각된 표면에서 관찰되는 결함들은 트렌치 식각동안 형성되는 이러한 잔류막의 두께에 크게 의존하는 것으로 나타났다.