• 대한금속재료학회지
• /
• 제47권1호
• /
• pp.38-43
• /
• 2009

To investigate the effect of RF power on the structural, optical and electrical properties of amorphous InGaZnO (a-IGZO), its thin films and TFTs were prepared by RF magnetron sputtering method with different RF power conditions of 40, 80 and 120 W at room temperature. In this study, as RF power during the deposition process increases, the RMS roughness of a-IGZO films increased from 0.26 nm to 1.09 nm, while the optical band-gap decreased from 3.28 eV to 3.04 eV. In the case of the electrical characteristics of a-IGZO TFTs, the saturation mobility increased from $7.3cm^2/Vs$ to $17.0cm^2/Vs$, but the threshold voltage decreased from 5.9 V to 3.9 V with increasing RF power. It is regarded that the increment of RF power increases the carrier concentration of the a-IGZO semiconductor layer due to the higher generation of oxygen vacancies.

• 한국재료학회지
• /
• 제1권2호
• /
• pp.65-70
• /
• 1991

$ZnO-Bi_2O_3-CoO-Sb_2O_3$와 $ZnO-Bi_2O_3-CoO-Sb_2O_3-Cr_2O_3$계에서 미세구조 변화 및 전기적 특성에 미치는 개재물의 영향을 조사하였다. 소결동안에 ZnO입자 성장은 스피넬 입자들에 의해 제어되었으며, 스피넬 입자들의 양의 증가에 의해 입자성장은 감소하였다. $Cr_2O_3(0.5mol\%)$의 첨가는 비직선성지수에는 큰 영향을 미치지 못하였으며 임계전압(breakdown voltage)을 증가시켰다. 계산에 의해 구한 장벽전압은 $ZnO-Bi_2O_3-CoO-Sb_2O_3$와 $ZnO-Bi_2O_3-CoO-Sb_2O_3-Cr_2O_3$ 계에서 각각 3.1V와 2.9V이었다.

• 한국의류학회지
• /
• 제47권3호
• /
• pp.577-592
• /
• 2023

In this study, nanofiber-based textile sensors were developed for motion detection and monitoring. Poly(vinylidene fluoride) (PVDF) nanofibers containing zinc oxide (ZnO) nanoparticles and silver nanowires (AgNW) were fabricated using electrospinning. PVDF was chosen as a piezoelectric polymer, zinc oxide as a piezoelectric ceramic, and AgNW as a metal to improve electric conductivity. The PVDF/ZnO/AgNW nanocomposite fibers were used to develop a textile sensor, which was then incorporated into an elbow band to develop a wearable smart band. Changes in the output voltage and peak-to-peak voltage (V_p-p) generated by the joint's flexion and extension were investigated using a dummy elbow. The β-phase crystallinity of pure PVDF nanofibers was 58% when analyzed using Fourier transform infrared spectroscopy; however, the β-phase crystallinity increased to 70% in PVDF nanofibers containing ZnO and to 78% in PVDF nanocomposite fibers containing both ZnO and AgNW. The textile sensor's output voltage values varied with joint-bending angle; upon increasing the joint angle from 45° to 90° to 150°, the V_p-p value increased from 0.321 V_p-p to 0.542 V_p-p to 0.660 V_p-p respectively. This suggests that the textile sensor can be used to detect and monitor body movements.

• 한국전기전자재료학회논문지
• /
• 제24권9호
• /
• pp.697-700
• /
• 2011

Thin-film transistors(TFTs) with magnesium zinc tin oxide(MZTO) channel layer are fabricated by solution-process. The threshold voltage (Vth) shifted toward positive directly with increasing Mg contents in MZTO system. Because the Mg has a lower standard electrode potential (SEP) than Sn, Zn, thus degenerate the oxygen vacancy ($V_O$). As a result, the Mg act as carrier suppressor and oxygen binder in the MZTO as well as a Vth controller.

• 한국진공학회지
• /
• 제18권5호
• /
• pp.394-401
• /
• 2009

본 논문은 ZnO 분말 타겟을 스퍼터링하여 glass 기판 위에 증착한 ZnO 박막의 구조적, 광학적 특성을 보고한다. 소결된 ZnO ceramic target을 사용하는 보통의 radio-frequency magnetron sputtering과 달리 본 연구에서는 전처리과정이 필요하지 않은 ZnO 분말 target을 사용하였다. ZnO 박막은 wurtzite (0002) 우선배향면으로 성장하였다. 초기의 ZnO 박막은 매우 평평한 층구조로 증착되었고, 두께가 증가함에 따라 섬구조로 전이하였다. 400-1000 nm 광원에 대하여 평균 88% 이상의 광투과도를 나타내었으며, 220 nm 시편의 경우, 3.23 eV의 near bandedge emission 흡수단을 측정하였다.

• Transactions on Electrical and Electronic Materials
• /
• 제13권2호
• /
• pp.64-68
• /
• 2012

We have successfully demonstrated a bandgap alteration of transparent zinc oxide (ZnO) thin film with Mg dopant by using sol-gel spin coating technique. By increasing the dopant from 0 to 30 atomic percent (at.%), a decrement value in the cutoff is observed, where the absorption edge shifts continuously to the shorter wavelength side, towards 300 nm. This resulted in a significant bandgap increment from 3.28 to 3.57 eV. However, the transmittance of the thin film at 350-800 nm gradually downgraded, from 93 to 80 % which is most probably due to the grain size that becomes bigger, and it also affected the electrical properties. The decrement from 45 to 0.05 mA at +10 V was observed in the I-V characteristics, concluding the significant relationship; where higher optical bandgap materials will exhibit lower conductivity. These findings may be useful in optoelectronics devices.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.334-334
• /
• 2012

Transparent oxide semiconductors have recently attracted much attention as channel layer materials due to advantageous electrical and optical characteristics such as high mobility, high stability, and good transparency. In addition, transparent oxide semiconductor can be fabricated at low temperature with a low production cost and it permits highly uniform devices such as large area displays. A variety of thin film transistors (TFTs) have been studied including ZnO, InZnO, and InGaZnO as the channel layer. Recently, there are many studies for substitution of Ga in InGaZnO TFTs due to their problem, such as stability of devices. In this work, new quaternary compound materials, tantalum-indium-tin oxide (TaInSnO) thin films were fabricated by using co-sputtering and used for the active channel layer in thin film transistors (TFTs). We deposited TaInSnO films in a mixed gas (O2+Ar) atmosphere by co-sputtering from Ta and ITO targets, respectively. The electric characteristics of TaInSnO TFTs and thin films were investigated according to the RF power applied to the $Ta_2O_5$ target. The addition of Ta elements could suppress the formation of oxygen vacancies because of the stronger oxidation tendency of Ta relative to that of In or Sn. Therefore the free carrier density decreased with increasing RF power of $Ta_2O_5$ in TaInSnO thin film. The optimized characteristics of TaInSnO TFT showed an on/off current ratio of $1.4{\times}108$, a threshold voltage of 2.91 V, a field-effect mobility of 2.37 cm2/Vs, and a subthreshold swing of 0.48 V/dec.

• 한국표면공학회지
• /
• 제41권1호
• /
• pp.12-15
• /
• 2008

The zinc oxide(ZnO) nanowires were deposited on Si(001) substrates by thermal chemical vapour deposition without any catalysts. SEM data suggested that the grown nanostructures were the well-aligned ZnO single crystals with preferential orientation. Back-gate ZnO nanowire field effect transistors(FET) were successfully fabricated using a photolithography process. The fabricated nanowire FET exhibits good contact between the ZnO nonowire and Au metal electrodes. Based on I-V characteristics it was found out that the ZnO nanowire revealed a characteristic of n-type field effect transistor. The drain current increases with increasing drain voltage, and the slopes of the $I_{ds}-V_{ds}$ curves are dependent on the gate voltage.

• 한국재료학회지
• /
• 제20권9호
• /
• pp.463-466
• /
• 2010

We studied the initial reaction mechanism of Zn precursors, namely, di-methylzinc ($Zn(CH_3)_2$, DMZ) and diethylzinc ($Zn(C_2H_5)_2$, DEZ), for zinc oxide thin-film growth on a Si (001) surface using density functional theory. We calculated the migration and reaction energy barriers for DMZ and DEZ on a fully hydroxylized Si (001) surface. The Zn atom of DMZ or DEZ was adsorbed on an O atom of a hydroxyl (-OH) due to the lone pair electrons of the O atom on the Si (001) surface. The adsorbed DMZ or DEZ migrated to all available surface sites, and rotated on the O atom with low energy barriers in the range of 0.00-0.13 eV. We considered the DMZ or DEZ reaction at all available surface sites. The rotated and migrated DMZs reacted with the nearest -OH to produce a uni-methylzinc ($-ZnCH_3$, UMZ) group and methane ($CH_4$) with energy barriers in the range of 0.53-0.78 eV. In the case of the DEZs, smaller energy barriers in the range of 0.21-0.35 eV were needed for its reaction to produce a uni-ethylzinc ($-ZnC_2H_5$, UEZ) group and ethane ($C_2H_6$). Therefore, DEZ is preferred to DMZ due to its lower energy barrier for the surface reaction.

• 한국재료학회지
• /
• 제21권2호
• /
• pp.120-124
• /
• 2011

Silicon heterojunction solar cells have been studied by many research groups. In this work, silicon heterojunction solar cells having a simple structure of Ag/ZnO:Al/n type a-Si:H/p type c-Si/Al were fabricated. Samples were fabricated to investigate the effect of transparent conductive oxide growth conditions on the interface between ZnO:Al layer and a-Si:H layer. One sample was deposited by ZnO:Al at low working pressure. The other sample was deposited by ZnO:Al at alternating high working pressure and low working pressure. Electrical properties and chemical properties were investigated by light I-V characteristics and AES method, respectively. The light I-V characteristics showed better efficiency on sample deposited by ZnO:Al by alternating high working pressure and low working pressure. Atomic concentrations and relative oxidation states of Si, O, and Zn were analyzed by AES method. For poor efficiency samples, Si was diffused into ZnO:Al layer and O was diffused at the interface of ZnO:Al and Si. Differentiated O KLL spectra, Zn LMM spectra, and Si KLL spectra were used for interface reaction and oxidation state. According to AES spectra, sample deposited by high working pressure was effective at reducing the interface reaction and the Si diffusion. Consequently, the efficiency was improved by suppressing the SiOx formation at the interface.