• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.324-327
• /
• 2000

In this paper, the effects of negative and positive bias stress on p-channel poly-Si TFT's fabricated by excimer laser annealing have been investigated After positive and negative bias stress, transcon-ductance(g$_{m}$) is increased because of a reduction of the effective channel length due to the injected electron in the gate oxide. In the positive bias stress, the injection of hole is appeared after stress time of 3600sec and g$_{m}$ is decreased. On the other hand, the gate voltage at the maximum g$_{m}$, S-swing and threshold voltage(V$_{th}$) are decreased because of the interface state generation due to the injection of electrons into the gate oxide.e.ide.e.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2009년도 춘계학술대회 논문집
• /
• pp.177-181
• /
• 2009

Compositional gradient CrNx coatings were fabricated using arc ion plating in Ar/$N_2$ gaseous mixture by gradually increasing $N_2$ flux rate from 0 to 120 SCCM. The effect of negative substrate bias on the film microstructure and mechanical properties were systematically investigated with XRD, GDOES, and SEM. The results show that substrate bias has an important influence on film growth and microstructure of gradient CrNx coatings. The coatings mainly crystallized in the mixture of hexagonal $Cr_{2}N$ and fcc CrN phases. By increasing substrate bias, film microstructure evolved from an apparent columnar structure to an equiaxed one. With increasing substrate bias, deposition rate first increased, and then decreased. The maximum of deposition rate was 15 nm/min obtained at a bias of -50V.

• 한국표면공학회지
• /
• 제32권3호
• /
• pp.303-306
• /
• 1999

On the effect of substrate bias at first stage of diamond synthesis at lower substrate temperature(approximately 673K) using microwave plasma CVD and effect of reaction gas system for the bias enhanced nucleation were studied. The reaction gas was mixture of methane and hydrogen or carbon monoxide and hydrogen. The nucleation density of applied bias -150V using $CH_4-H_2$ reaction gas system, significantly higher than that of $C-H_2$ reaction gas system. When the $CH_4-H_2$ reaction was used, nucleation density was increased because of existence of SiC as a interface for diamond nucleation. By use of this negative bias effect for fabrication of CVD diamond film using two-step diamond growth without pre-treatment, fabrication of the diamond film consist of diamond grains $0.2\mu\textrm{m}$ in diameter was demonstrated

• 한국전기전자재료학회논문지
• /
• 제21권8호
• /
• pp.687-694
• /
• 2008

This paper is focused on the improvement of MOS device reliability related to deuterium process. The injection of deuterium into the gate oxide film was achieved through two kind of method, high-pressure annealing and low-energy implantation at the back-end of line, for the purpose of the passivation of dangling bonds at $SiO_2/Si$ interface. Experimental results are presented for the degradation of 3-nm-thick gate oxide ($SiO_2$) under both negative-bias temperature instability (NBTI) and hot-carrier injection (HCI) stresses using P and NMOSFETs. Annealing process was rather difficult to control the concentration of deuterium. Because when the concentration of deuterium is redundant in gate oxide excess traps are generated and degrades the performance, we found annealing process did not show the improved characteristics in device reliability, compared to conventional process. However, deuterium ion implantation at the back-end process was effective method for the fabrication of the deuterated gate oxide. Device parameter variations under the electrical stresses depend on the deuterium concentration and are improved by low-energy deuterium implantation, compared to conventional process. Our result suggests the novel method to incorporate deuterium in the MOS structure for the reliability.

• E2M - 전기 전자와 첨단 소재
• /
• 제7권1호
• /
• pp.57-63
• /
• 1994

Aluminum oxide($Al_2{O_3}$) offers some unique advantages over the conventional silicon dioxide( $SiO_{2}$) gate insulator: greater resistance to ionic motion, better radiation hardness, possibility of obtaining low threshold voltage MOS FETs, and possibility of use as the gate insulator in nonvolatile memory devices. We have undertaken a study of the dielectric breakdown of $Al_2{O_3}$ on Si deposited by GAIVBE technique. In our experiments, we have varied the $Al_2{O_3}$ thickness from 300.angs. to 1400.angs. The resistivity of $Al_2{O_3}$ films varies from 108 ohm-cm for films less than 100.angs. to 10$_{13}$ ohm-cm for flims on the order of 1000.angs. The flat band shift is positive, indicating negative charging of oxide. The magnitude of the flat band shift is less for negative bias than for positive bias. The relative dielectric constant was 8.5-10.5 and the electric breakdown fields were 6-7 MV/cm(+bias) and 11-12 MV/cm (-bias).

• 한국항만경제학회지
• /
• 제30권3호
• /
• pp.1-14
• /
• 2014

BDI건화물운임지수의 변동성은 환율과 주가의 변동성을 크게 초과할 정도로 대단히 클 뿐만 아니라 변동성이 점차 커지고 있어서 운임을 예측하는데 많은 어려움을 겪고 있다. 이에 본고는 이러한 운임지수의 변동성을 정확히 포착할 수 있는 모형을 찾는데 목적을 둔다. 이를 위해 변동성 분석에 흔히 사용되는 대칭형 변동성 모형인 GARCH 모형과 비대칭 변동성 모형인 AGARCH모형, GJR모형, EGARCH모형을 도입한다. 그것은 나쁜 뉴스가 좋은 뉴스보다 더 큰 변동성을 야기할 가능성이 높기 때문이다. 먼저 운임의 예측불가능요소를 운임의 요일별 특성을 제거한 후 자기회귀를 하여 구한 후 GARCH 분석을 적용하는데 적합한 성격을 갖는가를 조사한다. 비대칭모형의 AGARCH모형에서는 비대칭을 나타내는 계수가 유의하나 부호가 모형의 예상과 달라 나쁜 뉴스가 좋은 뉴스보다 더 큰 변동성을 야기하지 않으며, EGARCH모형의 비대칭계수도 양의 부호로 모형의 예상과 반대일 뿐만 아니라 유의하지 않아 나쁜 뉴스가 좋은 뉴스보다 더 큰 변동성을 야기하지 않는다는 것, 그리고 GJR모형에서도 해당 계수가 음으로 모형과 반대로 유의하지 않아 음의 충격이 양의 충격보다 더 큰 변동성을 유발하지 않음을 보인다. 이에 따라 BDI건화물운임지수의 변동성은 GARCH모형을 이용하는 것이 합리적이라는 점을 보인다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 센서 박막재료
• /
• pp.35-37
• /
• 2001

The Al etching was studied employing negative ions generated in the downstream $Cl_2$ plasma. In order to etch the Al film practically on an insulator covered electrode coupled with RF power, reduction of the negative self bias voltage (Vdc) was examined using a magnetic filter which trapped electrons. Addition of $SF_6$ and $H_2$ to a $Cl_2/BCl_3$ mixture reduced significantly Vdc.

• Asian-Australasian Journal of Animal Sciences
• /
• 제15권8호
• /
• pp.1222-1226
• /
• 2002

Estimates of genetic correlation between direct and maternal effects for weaning weight of beef cattle are often negative in field data. The biological existence of this genetic antagonism has been the point at issue. Some researchers perceived such negative estimate to be an artifact from poor modeling. Recent studies on sources affecting the genetic correlation estimates are reviewed in this article. They focus on heterogeneity of the correlation by sex, selection bias caused from selective reporting, selection bias caused from splitting data by sex, sire by year interaction variance, and sire misidentification and inbreeding depression as factors contributing sire by year interaction variance. A biological justification of the genetic antagonism is also discussed. It is proposed to include the direct-maternal genetic covariance in the analytical models.

• 한국진공학회지
• /
• 제12권S1호
• /
• pp.36-39
• /
• 2003

Field-domain dynamics and current self-oscillations are theoretically studied in quantum-well (QW) negative-effective-mass (NEM) $p^{+}pp^{+}$ diodes when the electric field is applied along the direction of the well. The origin of current self-oscillations is the formation and traveling of electric-field domains in the p-base. We have accurately considered the scattering contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon. It's indicated that, both the applied bias and the doping concentration largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM $p^{+}pp^{+}$ diode with a submicrometer p-base. The complicated field-domain dynamics is presented with the applied bias as the controlling parameter.

• 전자공학회논문지SC
• /
• 제40권6호
• /
• pp.16-23
• /
• 2003

본 논문에서 보청기를 위한 개별 BJT 소자의 효과적인 바이어스 회로를 제안한다. 보청기에 널리 사용되는 컬렉터 귀환 바이어스 회로는 부귀환 저항을 가지고 있다. 이 저항은 AC와 DC에 동시에 영향을 줌으로서 DC 바이어스 점의 변화 없이 증폭기의 이득을 변화시키기 어렵다. 또한 기존회로는 보청기의 이득이 높을 경우 전원 잡음의 정귀환으로 발진할 수 있는 단점이 있다. 제안된 회로는 컬렉터 귀환 바이어스회로에 베이스와 전원 사이에 컬렉터 저항보다 β배 더 큰 저항을 추가하여 기존회로의 두 가지 단점을 줄일 수 있다. 제안된 회로에서 DC 바이어스 점의 변화 없이 증폭기의 이득을 변경 할 수 있고 모의실험에서 기존회로보다 전원 잡음 이득을 18.5%정도 감소시킬 수 있다.