• Transactions on Electrical and Electronic Materials
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• 제13권4호
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• pp.192-195
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• 2012

We reported diborane ($B_2H_6$) doped wide bandgap hydrogenated amorphous silicon oxide (p-type a-SiOx:H) films prepared by using silane ($SiH_4$) hydrogen ($H_2$) and nitrous oxide ($N_2O$) in a radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) system. We improved the $E_{opt}$ and conductivity of p-type a-SiOx:H films with various $N_2O$ and $B_2H_6$ ratios and applied those films in regards to the a-Si thin film solar cells. For the single layer p-type a-SiOx:H films, we achieved an optical band gap energy ($E_{opt}$) of 1.91 and 1.99 eV, electrical conductivity of approximately $10^{-7}$ S/cm and activation energy ($E_a$) of 0.57 to 0.52 eV with various $N_2O$ and $B_2H_6$ ratios. We applied those films for the a-Si thin film solar cell and the current-voltage characteristics are as given as: $V_{oc}$ = 853 and 842 mV, $J_{sc}$ = 13.87 and 15.13 $mA/cm^2$. FF = 0.645 and 0.656 and ${\eta}$ = 7.54 and 8.36% with $B_2H_6$ ratios of 0.5 and 1% respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.346.2-346.2
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• 2016

The rear side contact recombination in the crystalline silicon solar cell could be reduced by back surface field. We formed polycrystalline silicon as a back surface field through crystallization of amorphous silicon. A thin silicon oxide applied to the passivation layer. We used quasi-steady-state photoconductance measurement to analyze electrical properties with various annealing condition. And, blister formed on surface of wafer during the annealing process. We observed the blister after varied annealing process with wafer of various surface. Shape and density of blister is influenced by various annealing temperature and process time. As the annealing temperature became higher, the average diameter of blister is decreased and total number of blister is increased. The sample with the $600^{\circ}C$ annealing temperature and 1 min annealing time exhibited the highest implied open circuit voltage and lifetime. We predicted that the various shape and density of blister affects the lifetime and implied open circuit voltage.

• 한국산학기술학회논문지
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• 제19권1호
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• pp.699-704
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• 2018

일차원 나노구조물은 양자 갇힘 효과 및 나노와이어가 갖는 체적 대비 높은 표면적 비에 기인하는 독특한 전기적, 광학적, 광전기적, 전기화학적 특성으로 인하여 많은 주목을 받아왔다. 특히 수직으로 성장된 나노와이어는 체적 대비 높은 표면적 비의 특성을 나타낸다. VLS(Vapor-Liquid-Soild) 공정은 나노구조물의 성장 과정에서 자기정렬 효과 때문에 더욱 주목을 받는다. 본 연구에서는 두 영역 열화학 기상증착법을 이용하여 Si\$SiO_2$(300 nm)\Pt 기판 위에 수직으로 정렬된 실리콘 옥사이드 나노기둥을 VLS 공정으로 성장시켰다. 성장된 실리콘 옥사이드 나노기둥의 형상과 결정학적 특성을 주사전자현미경 및 투과전자현미경으로 분석하였다. 그 결과 성장된 실리콘 옥사이드 나노기둥의 지름과 길이는 촉매 박막의 두께에 따라 변하였다. 실리콘 옥사이드 나노 기둥의 몸체는 비정질 상을 나타내었으며, Si과 O로 구성되어 있었다. 또한 성장된 실리콘 옥사이드 나노 기둥의 머리는 결정성을 나타내었으며, Si, O, Pt 및 Ti으로 구성되어 있었다. 실리콘 옥사이드 나노 기둥의 수직 정렬은 촉매물질인 Pt/Ti 합금의 결정성 정렬 선호에 기인하는 것으로 판단되며, 수직 성장된 실리콘 옥사이드 나노기둥은 기능성 나노소재로 활용이 가능할 것으로 기대된다.

• 전기학회논문지
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• 제65권10호
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• pp.1694-1696
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• 2016

Present thin film solar cells with hydrogenated amorphous silicon oxide (a-SiO:H) as an absorber suffer from low fill factor(FF) of 61~64 [%] in spite of its benefits related to high open circuit voltage ($V_{oc}$). Since degraded quality of a-SiO:H absorber by alloying with oxygen can affect the FF, we aimed to achieve high photosensitivity by minimizing $CO_2$ gas addition. Improving optical gap($E_{opt}$) has been attained by strong hydrogen dilution combined with lowering substrate temperature down to 100 [$^{\circ}C$]. Small amount of the $CO_2$ was added in order to disturb microcrystalline formation by high hydrogen dilution. The developed a-SiO:H has high photosensitivity (${\sim}2{\times}10^5$) and high $E_{opt}$ of 1.85 [eV], which contributed to attain remarkable FF of 74 [%] and high $V_{oc}$ (>1 [V]). As a result, high power conversion efficiency of 7.18 [%] was demonstrated by using very thin absorber layer of only 100 [nm], even though we processed all experiment at extremely low temperature of 100 [$^{\circ}C$].

• 한국전기전자재료학회논문지
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• 제30권2호
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• pp.115-118
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• 2017

Highly photosensitive and wide bandgap amorphous silicon oxide (a-$SiO_x$:H) films were developed at low temperature ranges ($100{\sim}150^{\circ}C$) with employing plasma-enhanced chemical vapor deposition by optimizing $H_2/SiH_4$ gas ratio and $CO_2$ flow. Photosensitivity more than $10^5$ and wide bandgap (1.81~1.85 eV) properties were used for making the a-$SiO_x$:H thin film solar cells, which exhibited a high open circuit voltage of 0.987 V at the substrate temperature of $100^{\circ}C$. In addition, a power conversion efficiency of 6.87% for the cell could be improved up to 7.77% by employing a new n-type nc-$SiO_x$:H/ZnO:Al/Ag triple back-reflector that offers better short circuit currents in the thin film photovoltaic devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.351.2-351.2
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• 2014

Indium tin oxide (ITO) has a lot of variations of its properties because it is basically in an amorphous state. Therefore, the differences in composition ratio of ITO can result in alteration of electrical properties. Normally, ITO is considered as transparent conductive oxide (TCO), possessing excellent properties for the optical and electrical devices. Quantitatively, TCO has transparency over 80 percent within the range of 380nm to 780nm, which is visible light although its specific resistance is less than $10-3{\Omega}/cm$. Thus, the solar cell is the best example for which ITO has perfectly matching profile. In addition, when ITO is used as transparent conductive electrode, this material essentially has to have a proper work function with contact materials. For instance, heterojunction with intrinsic thin layer (HIT) solar cell could have both front ITO and backside ITO. Because each side of ITO films has different type of contact materials, p-type amorphous silicon and n-type amorphous silicon, work function of ITO has to be modified to transport carrier with low built-in potential and Schottky barrier, and approximately requires variation from 3 eV to 5 eV. In this study, we examine the change of work function for different sputtering conditions using ultraviolet photoelectron spectroscopy (UPS). Structure of ITO films was investigated by spectroscopic ellipsometry (SE) and scanning electron microscopy (SEM). Optical transmittance of the films was evaluated by using an ultraviolet-visible (UV-Vis) spectrophotometer

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.199-199
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• 2008

이 실험은 NVM의 Oxide, Nitride, Oxide nitride층별 blocking, trapping and tunneling 속성에 대해서 밝히고자 한다. gate 전극은 값싸고 전도도가 좋은 알루미늄을 사용한다. 유리기판위에 Silicon nitride층을 20nm로 코팅하고 Silicon dioxide층을 10nm로 코팅한다. 그리고 amorphous Silicon material이 증착된다. Poly Silicon은 Solid Phase Crystallization 방법을 사용하였다. 마지막 공정으로 p-doping은 ion shower에 의한 방법으로 drain과 source 전극을 생성하였다. gate가 biasing 될 때, p-channel은 source와 drain 사이에서 형성된다. Oxide Nitride Oxide nitride (ONO) 층은 각각 12.5nm/20nm/2.3nm의 두께로 만들었다. 전하는 Program process 중에 poly Silicon층에서 Silicon Oxide nitride tunneling층을 통하여 움직이게 된다. 그리고 전하들은 Silicon Nitride층에 머무르게 된다. 그 전하들은 erasing process 중에 trapping 층에서 poly Silicon 층으로 되돌아 간다. Silicon Oxide blocking층은 trapping층으로 전하가 나가는 것을 피하기 위하여 더해진다. 이 논문에서 Programming process와 erasing process의 Id-Vg 특성곡선을 설명한다. Programming process에 positive voltage를 또는 erasing process에 negative voltage를 적용할 때, Id-Vg 특성 곡선은 왼쪽 또는 오른쪽으로 이동한다. 이 실험이 보여준 결과값에 의해서 10년 이상의 저장능력이 있는 메모리를 만들 수 있다. 그러므로, NVM의 중요한 두 가지 성질은 유지성과 내구성이다.

• 전자공학회논문지D
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• 제34D권1호
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• pp.35-40
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• 1997

A new method to form the gate oxide and recrystllize the polycrystalline silicon (poly-Si) active layer simultaneously is proposed and fabricated successfully. During te irradiation of excimer laser, the poly-Si film is recrystallized, while the oxygen ion impurities injected into the amorphous silicon(a-Si) film are activated by laser energy and react with silicon atoms to form SiO2. We investigated the characteristics of the sample fabricated by proposed method using AES, TEM, AFM. The electrical performance of oxide was verified by ramp up voltage method. Our experimental results show that a high quality oxide, a pol-Si film with fine grain, and a smooth and clean interface between oxide and poly-Si film have been successfully obtained by the proposed fabrication method. The interface roughness of oxide/poly-Si fabricated by new method is superior to film by conventional fabrication os that the proposed method may improve the performance of poly-Si TFTs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.426.1-426.1
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• 2016

We report high work function Aluminum doped zinc oxide (AZO) films as insertion layer as a function of O2 flow rate between transparent conducting oxides (TCO) and hydrogenated amorphous silicon oxide (a-SiOx:H) layer to improve open circuit voltage (Voc) and fill factor (FF) for high efficiency thin film solar cell. However, amorphous silicon (a-Si:H) solar cells exhibit poor fill factors due to a Schottky barrier like impedance at the interface between a-SiOx:H windows and TCO. The impedance is caused by an increasing mismatch between the work function of TCO and that of p-type a-SiOx:H. In this study, we report on the silicon thin film solar cell by using as insertion layer of O2 reactive AZO films between TCO and p-type a-SiOx:H. Significant efficiency enhancement was demonstrated by using high work-function layers (4.95 eV at O2=2 sccm) for engineering the work function at the key interfaces to raise FF as well as Voc. Therefore, we can be obtained the conversion efficiency of 7 % at 13mA/cm2 of the current density (Jsc) and 63.35 % of FF.

• 한국세라믹학회지
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• 제31권1호
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• pp.74-78
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• 1994

Degradation of thin oxide by doped poly-Si and its improvement were studied. The gate oxide can be degraded by phosphorous in poly-Si doped POCl3. The degradation is increased with the decrement of sheet resistance and poly-Si thickness. Oxide failures of amorphous-Si are higher than those of poly-Si. In-situ double deposition of amorphous-Si, 54$0^{\circ}C$/30 nm, and poly-Si, 6$25^{\circ}C$/220 nm, forms the mismatch structure of grain boundary between amorphous-Si and poly-Si, and suppresses the excess phosphorous on oxide surface by the mismatch structure. The control of phosphorous through grain boundary improves the oxide reliability.