• 한국결정성장학회지
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• 제19권2호
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• pp.75-78
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• 2009

PBN 도가니를 이용하여 Si이 도핑된 GaAs 단결정을 수직경사 응고법으로 성장시켰다. PBN 도가니에 산화막인 $B_{2}O_{3}$의 양을 $0{\sim}0.2wt%$ 범위에서 변화시키면서, 성장 후 캐리어 농도를 측정하였다. $B_{2}O_{3}$ 첨가량이 증가함에 따라, 초기 0.1 정도의 Si 도판트의 편석계수는 0.01 부근까지 급격히 감소하고, 동시에 캐리어 농도도 감소하는 것을 알 수 있었다. 이는 성장도중 도판트인 Si이 $B_{2}O_{3}$과 반응하며 도너인 Si 양을 감소시키며, 동시에 억셉터인 B 양을 증가시키기 때문으로 보인다. 한편 PBN 도가니 내면에 얇은 유리질의 $B_{2}O_{3}$층 형성이 용이한 고온 산화막 처리가 결함감소에 효과적임을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.154-155
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• 2012

The promise of nano-crystalites (nc) as a technological material, for applications including display backplane, and solar cells, may ultimately depend on tailoring their behavior through doping and crystallinity. Impurities can strongly modify electronic and optical properties of bulk and nc semiconductors. Highly doped dopant also effect structural properties (both grain size, crystal fraction) of nc-Si thin film. As discussed in several literatures, P atoms or radicals have the tendency to reside on the surface of nc. The P-radical segregation on the nano-grain surfaces that called self-purification may reduce the possibility of new nucleation because of the five-coordination of P. In addition, the P doping levels of ${\sim}2{\times}10^{21}\;at/cm^3$ is the solubility limitation of P in Si; the solubility of nc thin film should be smaller. Therefore, the non-activated P tends to segregate on the grain boundaries and the surface of nc. These mechanisms could prevent new nucleation on the existing grain surface. Therefore, most researches shown that highly doped nc-thin film by using conventional PECVD deposition system tended to have low crystallinity, where the formation energy of nucleation should be higher than the nc surface in the intrinsic materials. If the deposition technology that can make highly doped and simultaneously highly crystallized nc at low temperature, it can lead processes of next generation flexible devices. Recently, we are developing a novel CVD technology with a neutral particle beam (NPB) source, named as neutral beam assisted CVD (NBaCVD), which controls the energy of incident neutral particles in the range of 1~300eV in order to enhance the atomic activation and crystalline of thin films at low temperatures. During the formation of the nc-/pm-Si thin films by the NBaCVD with various process conditions, NPB energy directly controlled by the reflector bias and effectively increased crystal fraction (~80%) by uniformly distributed nc grains with 3~10 nm size. In the case of phosphorous doped Si thin films, the doping efficiency also increased as increasing the reflector bias (i.e. increasing NPB energy). At 330V of reflector bias, activation energy of the doped nc-Si thin film reduced as low as 0.001 eV. This means dopants are fully occupied as substitutional site, even though the Si thin film has nano-sized grain structure. And activated dopant concentration is recorded as high as up to 1020 #/$cm^3$ at very low process temperature (＜ $80^{\circ}C$) process without any post annealing. Theoretical solubility for the higher dopant concentration in Si thin film for order of 1020 #/$cm^3$ can be done only high temperature process or post annealing over $650^{\circ}C$. In general, as decreasing the grain size, the dopant binding energy increases as ratio of 1 of diameter of grain and the dopant hardly be activated. The highly doped nc-Si thin film by low-temperature NBaCVD process had smaller average grain size under 10 nm (measured by GIWAXS, GISAXS and TEM analysis), but achieved very higher activation of phosphorous dopant; NB energy sufficiently transports its energy to doping and crystallization even though without supplying additional thermal energy. TEM image shows that incubation layer does not formed between nc-Si film and SiO2 under later and highly crystallized nc-Si film is constructed with uniformly distributed nano-grains in polymorphous tissues. The nucleation should be start at the first layer on the SiO2 later, but it hardly growth to be cone-shaped micro-size grains. The nc-grain evenly embedded pm-Si thin film can be formatted by competition of the nucleation and the crystal growing, which depend on the NPB energies. In the evaluation of the light soaking degradation of photoconductivity, while conventional intrinsic and n-type doped a-Si thin films appeared typical degradation of photoconductivity, all of the nc-Si thin films processed by the NBaCVD show only a few % of degradation of it. From FTIR and RAMAN spectra, the energetic hydrogen NB atoms passivate nano-grain boundaries during the NBaCVD process because of the high diffusivity and chemical potential of hydrogen atoms.

• The Korean Journal of Ceramics
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• 제5권1호
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• pp.1-11
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• 1999

The effect of aliovalent dopents, $Nb_3O_5$ and MnO, on the grain growth kinetics of 12 mol% ceria stabilized tetragonal zirconia polycrystals (Ce-TZP) was studied. All specimens were sintered at $1550^{\circ}C$ for 20 minutes prior to annealing at different temperatures to study grain growth kinetics. Grain growth kinetics of Ce-TZP and 1 mol% $Nb_2O_5$ doped Ce-TZP (Ce-TZP/$Nb_3O_5$) during annealing at 1475, 1550, and $1600^{\circ}C$ adequately matched with square law $(D^2-D_\;o^2=k_at)$. However, grain growth in 1 mol% MnO suppressed grain growth in Ce-TZP by drag force exerted by $Mn^{+2}$ ions which segregated strongly to the positively-charged grain boundaries of Ce-TZP, $Nb_2O_5$ enhanced grain growth by increasing the concentration of vacancies of $Zr^{+4}$ ion and $Ce^{+4}$ ions. Surface analysis with X-ray photoelectron spectroscopy (XPS) showed the segregation of Mn+2 ions to grain boundaries. The kinetics of grain growth obtained in the base Ce-TZP and the Ce-TZPs with the aliovalent dopants were examined in the context of impurity drag effect and space charge effect.

• 한국전기전자재료학회논문지
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• 제31권1호
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• pp.6-10
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• 2018

Ni germanide (NiGe) is a promising alloy material with small contact resistance at the source/drain (S/D) of Ge MOSFETs. However, it is necessary to reduce the specific contact resistance between NiGe and the doped Ge S/D region in high-performance MOSFETs. In this study, a novel method is proposed to reduce the specific contact resistance between NiGe and p-type Ge (p-Ge) using a Tb interlayer. The specific contact resistance between NiGe and p-Ge was successfully decreased with the introduction of the Tb interlayer. To investigate the mechanism behind the reduction in the specific contact resistance, the elemental distribution and crystalline structure of NiGe were analyzed using secondary ion mass spectroscopy and X-ray diffraction. It is likely that the reduction in specific contact resistance was caused by an increase in the concentration of boron in the space between NiGe and p-Ge due to the influence of the Tb interlayer.