• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.527-531
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• 2016

In this study, p-type thin film transistors consisting of CuO channels were fabricated by sol-gel process, with copper (II) acetate monohydrate precursors. At $500^{\circ}C$, the deposited films were fully converted into monoclinic phase CuO. The fabricated CuO thin film transistors deliver field effect mobility in saturation regime of $0.015cm^2/Vs$, and $I_{on}/I_{off}$ of ${\sim}10^3$. The degradation of the performance of the fabricated CuO thin film transistor caused by the exposure to air has been studied.

• Proceedings of the Korean Ceranic Society Conference
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• 1986.12a
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• pp.287-304
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• 1986

High quality monocrystalline $\beta$-SiC thin films were grown via two-step process of conversion of the Si(100) surface by reaction with $C_2H_4$ and the subsequent chemical vapor deposition (CVD) at $1360^{\circ}C$ and 1 atm total pressure. Four dopants, B and Al and p-type, and N and P for n-type, were also incorporated into monocrystalline $\beta$-SiC thin films during the CVD growth process. IR and Raman spectroscopies were used to evaluate the quality of the undoped $\beta$-SiC thin films and to investigate the effects of dopants on the structure of the doped $\beta$-SiC thin films. The changes in the shape of IR and Raman spectra of the doped thin films due to dopants were observed. But the XTEM micrographs except for the B-doped and annealed films showed the same density and distribution of stacking faults and dislocations as was seen in the undoped samples, The IR and Raman spectra of the B-doped and annealed films showed the broad and weak bands and one extra peak at the 850 $cm^{-1}$ respectively. The SAD pattern and XTEM micrograph of the B-doped and annealed film provided the evidence for twinning.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.13-17
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• 2014

The direct-patternable $SnO_2$ thin film was successfully fabricated by photochemical metal-organic deposition. The composition and chemical bonding state of $SnO_2$ thin film were analyzed by using X-ray photoelectron spectroscopy (XPS) from the surface to the interface with Si substrate. XPS depth profiling analysis allowed the determination of the atomic composition in $SnO_2$ film as a function of depth through the evolution of four elements of C 1s, Si 2p, Sn 3d, and O 1s core level peaks. At the top surface, nearly stoichiometric $SnO_2$ composition (O/Sn ratio is 1.92.) was observed due to surface oxidation but deficiency of oxygen was increased to the interface of patterned $SnO_2/Si$ substrate where the O/Sn ratio was about 1.73~1.75 at the films. This O deficient state of the film may act as an n-type semiconductor and allow $SnO_2$ to be applied as a transparent electrode in optoelectronic applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.297.2-297.2
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• 2013

Scavenging electricity from wasteful energy resources is currently an important issue and piezoelectric nanogenerators (NGs) based on zinc oxide (ZnO) are promising energy harvesters that can be adapted to various portable, wearable, self-powered electronic devices. Although ZnO has several advantages for NGs, the piezoelectric semiconductor material ZnO generate an intrinsic piezoelectric potential of a few volts as a result of its mechanical deformation. As grown, ZnO is usually n-type, a property that was historically ascribed to native defects. Oxygen vacancies (Vo) that work as donors exist in ZnO thin film and usually screen some parts of the piezoelectric potential. Consequently, the ZnO NGs' piezoelectric power cannot reach to its theoretical value, and thus decreasing the effect from Vo is essential. In the present study, c-axis oriented insulator-like sputtered ZnO thin films were grown in various temperatures to fabricate an optimized nanogenerator (NGs). The purity and crystalinity of ZnO were investigated with photoluminescence (PL). Moreover, by introducing a p-type polymer usually used in organic solar cell, it was discussed how piezoelectric passivation effect works in ZnO thin films having different types of defects. Prepared ZnO thin films have both Zn vacancies (accepter like) and oxygen vacancies (donor like). It generates output voltage 20 time lager than n-type dominant semiconducting ZnO thin film without p-type polymer conjugating. The enhancement is due to the internal accepter like point defects, zinc vacancies (VZn). When the more VZn concentration increases, the more chances to prevent piezoelectric potential screening effects are occurred, consequently, the output voltage is enhanced. Moreover, by passivating remained effective oxygen vacancies by p-type polymers, we demonstrated further power enhancement.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.214-220
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• 2018

We report on the fabrication and photoelectrochemical(PEC) properties of a $Cu_2O$ thin film/ZnO nanorod array oxide p-n heterojunction structure with ZnO nanorods embedded in $Cu_2O$ thin film as an efficient photoelectrode for solar-driven water splitting. A vertically oriented n-type ZnO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type $Cu_2O$ thin film was directly electrodeposited onto the vertically oriented ZnO nanorods array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were characterized using X-ray diffraction and scanning electron microscopy as well as Raman scattering. The PEC properties of the fabricated $Cu_2O/ZnO$ p-n heterojunction photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the $Cu_2O/ZnO$ photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.77mA/cm^2$ at 0.5 V vs $Hg/HgCl_2$ in a $1mM\;Na_2SO_4$ electrolyte, revealing an effective operation of the oxide heterostructure. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs $Hg/HgCl_2$, which made the device self-powered. The observed PEC performance was attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential, including the light absorption and separation processes of photoinduced charge carriers.

• Transactions on Electrical and Electronic Materials
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• v.13 no.4
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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.

• Mass Spectrometry Letters
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• v.12 no.2
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• pp.47-52
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• 2021

Evaluating the impurity concentrations in semiconductor thin films using time of flight secondary ion mass spectrometry (ToF-SIMS) is an effective technique. The mass interference between isotopes and matrix element in data interpretation makes the process complex. In this study, we have investigated the doping concentration of phosphorus in, phosphorus doped silicon thin film on glass using ToF-SIMS in the dynamic mode of operation. To overcome the mass interference between phosphorus and silicon isotopes, the quantitative analysis of counts to concentration conversion was done following two routes, standard relative sensitivity factor (RSF) and SIMetric software estimation. Phosphorus doped silicon thin film of 180 nm was grown on glass substrate using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using ToF-SIMS, the phosphorus-31 isotopes were detected in the range of 10¹~10⁴ counts. The silicon isotopes matrix element was measured from p-type silicon wafer from a separate measurement to avoid mass interference. For the both procedures, the phosphorus concentration versus depth profiles were plotted which agree with a percent difference of about 3% at 100 nm depth. The concentration of phosphorus in silicon was determined in the range of 10¹⁹~10²¹ atoms/cm³. The technique will be useful for estimating distributions of various dopants in the silicon thin film grown on glass using ToF-SIMS overcoming the mass interference between isotopes.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.89-93
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• 2017

A thin film thermoelectric generator that consisted of 5 p/n pairs was fabricated with $1{\mu}m$-thick n-type $In_3Sb_1Te_2$ and p-type $Ge_2Sb_2Te_5$ deposited via radio frequency magnetron sputtering. First, $1{\mu}m$-thick GST and IST thin films were deposited at $250^{\circ}C$ and room temperature, respectively, via radio-frequency sputtering; these films were annealed from 250 to $450^{\circ}C$ via rapid thermal annealing. The optimal power factor was found at an annealing temperature of $400^{\circ}C$ for 10 min. To demonstrate thermoelectric generation, we measured the output voltage and estimated the maximum power of the n-IST/p-GST generator by imposing a temperature difference between the hot and cold junctions. The maximum output voltage and the estimated maximum power of the $1{\mu}m$-thick n-IST/p-GST TE generators are approximately 17.1 mV and 5.1 nW at ${\Delta}T=12K$, respectively.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.21-28
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• 1995

Electrical conductivity of $TiO_2$ thin films, deposited on $Al_2O_3$ substrates by metal organic chemical vapor deposition (MOCVD), was measured by four-point probe method in a temperature range from $800^{\circ}C$ to $1025^{\circ}C$ and an oxygen partial pressure range from $2.7{\times}10^{-5}$ atm to 1 atm. In the low oxygen partial pressure region n-type conduction was dominant, but in the high oxygen partial pressure region p-type conduction behavior appeared due to substitution of Ti ions by Al ions, which were diffused from the substrate during post deposition annealing process. Electrical conductivity of the film decreases in the n-type region and increases in the p-type region as the oxygen partial pressure increases. The transition points, which show the minimum conductivity, shifted to the higher oxygen partial pressure region as the measuring temperature increased, but it shifted to lower oxygen partial pressure region with an increase in the post annealing temperature. The results were also discussed with the possible defect models.

• Journal of IKEEE
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• v.20 no.2
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• pp.174-176
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• 2016

In this study, we maximize the temperature difference between the ends of a HgTe nanoparticle(NP) thin film on a thermoelectric platform with a through-substrate via. The thermoelectric characteristics of the HgTe NP thin film show p-type behavior and its Seebeck coefficient is $290{\mu}V/K$. In addition, we demonstrate the possibility of wearable thermoelectric devices transforming body heat into electricity from through-substrate via thermoelectric platforms on human skin.