• 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.

• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.63-69
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• 2022

Preparing various types of thin films of oxide semiconductors is a promising approach to fabricate efficient photoanodes and photocathodes for hydrogen production via photoelectrochemical (PEC) water splitting. In this work, we investigate the feasibility of an efficient photocathode for PEC water reduction of a p-type oxide semiconductor cupric oxide (CuO) thin film prepared via a facile method combined with sputtering Cu metallic film on fluorine-doped thin oxide (FTO) coated glass substrate and subsequent thermal oxidation of the sputtered Cu metallic film in dry air. Characterization of the structural, optical, and PEC properties of the CuO thin film prepared at various Cu sputtering powers reveals that we can obtain an optimum CuO thin film as an efficient PEC photocathode at a Cu sputtering power of 60 W. The photocurrent density and the optimal photocurrent conversion efficiency for the optimum CuO thin film photocathode are found to be -0.3 mA/cm² and 0.09% at 0.35 V vs. RHE, respectively. These results provide a promising route to fabricating earth-abundant copper-oxide-based photoelectrode for sunlight-driven hydrogen generation using a facile method.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.407-413
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• 1997

The crystallized CuPc(copper phthalocyanine) film on a p-type <100> Si substrate is prepared at the substrate temperature of $300^{\circ}C$ by thermal evaporation. X -ray diffraction analysis showed the CuPc film to have a-axis oriented structure. For the measurement of photovoltaic characteristics of the CuPc/Si film and the Si substrate, a transverse current-voltage (I-V) curve is observed. In the dark, the Au/Si junction is shown to be ohmic contact. However, under illumination, a photovoltaic effect is not observed. The I-V curve in the dark indicates that the CuPc film on Si may form an ohmic contact. Since the CuPc film is a p-type semiconductor, the CuPc/p-Si junction has no barrier at the interface. Under illumination, the CuPc/Si junction shows a large photocurrent comparing with that of the wafer. The result indicates that the CuPc layer plays an important role in the photocarrier generation under red illumination (600 nm). The CuPc/Si film shows the photo voltaic characteristics with a short-circuit photocurrent ($J_{sc}$) of $4.29\;mA/cm^{2}$ and an open-circuit voltage ($V_{oc}$) of 12 mA.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.156-161
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• 2015

The electronic structures of the potential candidate semiconductor nanoparticles for dye-sensitized solar cell (DSSC), such as $ZnSnO_3$ and $Zn_2SnO_4$, have been investigated by employing X-ray photoemission spectroscopy (XPS). The measured X-ray diffraction patterns show that $ZnSnO_3$ and $Zn_2SnO_4$ samples have the single-phase ilmenite-type structure and the inverse spinel structure, respectively. The measured Zn 2p and Sn 3d core-level XPS spectra reveal that the valence states of Zn and Sn ions are divalent (Zn 2+) and tetravalent (Sn 4+), respectively, in both $ZnSnO_3$ and $Zn_2SnO_4$. On the other hand, the shallow core-level measurements show that the binding energies of Sn 4d and Zn 3d core levels in $ZnSnO_3$ are lower than those in $Zn_2SnO_4$. This work provides the information on the valence states of Zn and Sn ions and their chemical bonding in $ZnSnO_3$ and $Zn_2SnO_4$.

• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.89-93
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• 2009

Amorphous $Ge_{1-x}Mn_x$ semiconductor thin films grown by low temperature vapor deposition were annealed, and their electrical and magnetic properties have been studied. The amorphous thin films were $1,000{\sim}5,000\;{\AA}$ thick. Amorphous $Ge_{1-x}Mn_x$ thin films were annealed at $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$ and $700^{\circ}C$ for 3 minutes in high vacuum chamber. X-ray diffraction analysis reveals that as-grown $Ge_{1-x}Mn_x$ semiconductor thin films are amorphous and are crystallized by annealing. Crystallization temperature of amorphous $Ge_{1-x}Mn_x$ semiconductor thin films varies with Mn concentration. Amorphous $Ge_{1-x}Mn_x$ thin films have p-type carriers and the carrier type is not changed during annealing, but the electrical resistivity increases with annealing temperature. Magnetization characteristics show that the as-grown amorphous $Ge_{1-x}Mn_x$ thin films are ferromagnetic and the Curie temperatures are around 130 K. Curie temperature and saturation magnetization of annealed $Ge_{1-x}Mn_x$ thin films increase with annealing temperature. Magnetization behavior and X-ray analysis implies that formation of ferromagnetic $Ge_3Mn_5$ phase causes the change of magnetic and electrical properties of annealed $Ge_{1-x}Mn_x$ thin films.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1375-1381
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• 2010

LED(Light Emitting Diode) is an emitting device which energy is same to the bandgap energy of p-type and n-type semiconductor junction. Recently high brightness LED is used in fish-luring light and traffic signal light alternative of normal light bulb, and widely used in the area of display pannel. Moreover nowadays LED has been used as a back light of LCD display. Recently, visible light communication(VLC) using LED, that allow two-way serial data communication between LEDs over a distance of sveral centimeters or meters, has been widely studied in the area of digital information transmission along with illumination and display. In this paper, we present LED communication system and their applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.226-229
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• 2010

LED(Light Emitting Diode) is an emitting device which energy is same to the bandgap of p-type and n-type semiconductor junction. Recently high brightness LED is used in fish-luring light and traffic signal light alternative of normal light bulb, and widely used in the area of display pannel. Moreover nowadays LED has been used as a back light of LCD display. Recently, visible light communication(VLC) using LED, that allow two-way serial data communication between LEDs over a distance of sveral centimeters or meters, has been widely studied in the area of digital information transmission along with illumination and display. In this paper, we present LED communication system and their applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.8-9
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• 2006

Hafnium oxide ($HfO_2$) thin films were deposited on p-type (100) silicon wafers by atomic layer deposition (ALD) using TEMAHf and $O_3$. Prior to the deposition of $HfO_2$ films, a thin Hf ($10\;{\AA}$) metal layer was deposited. Deposition temperature of $HfO_2$ thin film was $350^{\circ}C$ and its thickness was $150\;{\AA}$. Samples were then annealed using furnace heating to temperature ranges from 500 to $900^{\circ}C$. The MOS capacitor of round-type was fabricated on Si substrates. Thermally evaporated $3000\;{\AA}$-thick AI was used as top electrode. In this work, We study the interface characterization of $HfO_2$/Hf/Si MOS capacitor depending on annealing temperature. Through AES(Auger Electron Spectroscopy), capacitance-voltage (C-V) and current-voltage (I-V) analysis, the role of Hf layer for the better $HfO_2$/Si interface property was investigated. We found that Hf meta1 layer in our structure effective1y suppressed the generation of interfacial $SiO_2$ layer between $HfO_2$ film and silicon substrate.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.248-252
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• 1992

$ZrO_2-dopedYb_2O_3solid$ solutions containing 1, 3, 5, 7 and 9 mol% $ZrO_2were$ synthesized from spectroscopically pure $Yb_2O_3$ and $ZrO_2$ powders and found to be rare earth C-type structure by XRD technique. Electrical conductivities were measured as a function of temperatures from 700 to $1050^{\circ}C$ and oxygen partial pressures from 1${\times}$$10^-5$ to 2${\times}$ $10^-1$atm. The electrical conductivities depend simply on temperature and the activation energies are determined to be 1.56-1.68 $_eV$. The oxygen partial pressure dependence of the electrical conductivity shows that the conductivity increases with increasing oxygen partial pressure, indicating p-type semiconductor. The $PO_2$ dependence of the system is nearly power of 1/4. It is suggested from the linearity of the temperature dependence of electrical conductivity and only one value of 1/n that the solid solutions of the system have single conduction mechanism. From these results, it is concluded that the main defects of the system are negatively doubly charged oxygen interstitial in low. $ZrO_2doping$ level and negatively triply charged cation vacancy in high doping level and the electrical conduction is due to the electronic hole formed by the defect structure.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.509-514
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• 2020

The two key variables of an Si solar cell, i.e., emitter (n-type window layer) and base (p-type substrate) doping levels or concentrations, are studied using Medici, a 2-dimensional semiconductor device simulation tool. The substrate is p-type and 150 ㎛ thick, the pn junction is 2 ㎛ from the front surface, and the cell is lit on the front surface. The doping concentration ranges from 1 × 10¹⁰ cm^-3 to 1 × 10²⁰ cm^-3 for both emitter and base, resulting in a matrix of 11 by 11 or a total of 121 data points. With respect to increasing donor concentration (Nd) in the emitter, the open-circuit voltage (Voc) is little affected throughout, and the short-circuit current (Isc) is affected only at a very high levels of Nd, exceeding 1 × 10¹⁹ cm^-3, dropping abruptly by about 12%, i.e., from Isc = 6.05 × 10^-9 A·㎛^-1, at Nd = 1 × 10¹⁹ cm^-3 to Isc = 5.35 × 10^-9 A·㎛^-1 at Nd = 1 × 10²⁰ cm^-3, likely due to minority-carrier, or hole, recombination at the very high doping level. With respect to increasing acceptor concentration (Na) in the base, Isc is little affected throughout, but Voc increases steadily, i.e, from Voc = 0.29 V at Na = 1 × 10¹² cm^-3 to 0.69 V at Na = 1 × 10¹⁸ cm^-3. On average, with an order increase in Na, Voc increases by about 0.07 V, likely due to narrowing of the depletion layer and lowering of the carrier recombination at the pn junction. At the maximum output power (Pmax), a peak value of 3.25 × 10^-2 W·cm^-2 or 32.5 mW·cm^-2 is observed at the doping combination of Nd = 1 × 10¹⁹ cm^-3, a level at which Si is degenerate (being metal-like), and Na = 1 × 10¹⁷ cm^-3, and minimum values of near zero are observed at very low levels of Nd ≤ 1 × 10¹³ cm^-3. This wide variation in Pmax, even within a given kind of solar cell, indicates that selecting an optimal combination of donor and acceptor doping concentrations is likely most important in solar cell engineering.