• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.8
• /
• pp.481-485
• /
• 2015

We investigated the effects of annealing on the electrical and thermal properties of ZTO/4H-SiC heterojunction diodes. A ZTO thin film layer was grown on p-type 4H-SiC substrate by using solution process. The ZTO/SiC heterojunction structures annealed at $500^{\circ}C$ show that $I_{on}/I_{off}$ increases from ${\sim}5.13{\times}10^7$ to ${\sim}1.11{\times}10^9$ owing to the increased electron concentration of ZTO layer as confirmed by capacitance-voltage characteristics. In addition, the electrical characterization of ZTO/SiC heterojunction has been carried out in the temperature range of 300~500 K. When the measurement temperature increased from 300 K to 500 K, the reverse current variation of annealed device is higher than as-grown device, which is related to barrier height in the ZTO/SiC interface. It is shown that annealing process is possible to control the electrical characteristics of ZTO/SiC heterojunction diode.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.3
• /
• pp.149-153
• /
• 2012

The $Cu_2O/TiO_2$ inverse opal heterojunction arrays were developed by electrochemical deposition of $Cu_2O$ nanoparticles on $TiO_2$ inverse opal arrays. The $Cu_2O$ nanoparticles completely filled the inner pores of $TiO_2$ inverse opal film (prepared by liquid phase deposition with an average thickness of 400 nm) and covered the entire area; exhibiting high crystalline properties of anatase and cubic phase from $TiO_2$ and $Cu_2O$, respectively. From asymmetric current-voltage profile, it was noticeable that a heterojunction was well formed for charge transport from $Cu_2O$ to $TiO_2$ film resulting from the enhanced charge separation yield. In addition, increased photocurrent of 0.19 $mA/cm^2$ (versus 0.08 $mA/cm^2$ under dark condition) was obtained at -0.35 V from the heterojunction structure in the 0.5M $Na_2SO_4$ solution.

• Journal of the Korean institute of surface engineering
• /
• v.51 no.3
• /
• pp.185-190
• /
• 2018

Dopant-free silicon heterojunction solar cells using Transition Metal Oxide(TMO) such as Molybdenum Oxide($MoO_X$) and Vanadium Oxide($V_2O_X$) have been focused on to increase the work function of TMO in order to maximize the work function difference between TMO and n-Si for a high-efficiency solar cell. One another way to increase the work function difference is to control the silicon wafer resistivity. In this paper, dopant-free silicon heterojunction solar cells were fabricated using the wafer with the various resistivity and analyzed to understand the effect of n-Si work function. As a result, it is shown that the high passivation and junction quality when $V_2O_X$ deposited on the wafer with low work function compared to the high work function wafer, inducing the increase of higher collection probability, especially at long wavelength region. the solar cell efficiency of 15.28% was measured in low work function wafer, which is 34% higher value than the high work function solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.12
• /
• pp.808-812
• /
• 2015

Highly optical transparent photoelectric devices were realized by using a transparent metal-oxide semiconductor heterojunction of p-type NiO and n-type ZnO. A functional template of ITO nanowires (NWs) was applied to this transparent heterojunction device to enlarge the light-reactive surface. The ITO NWs/n-ZnO/p-NiO heterojunction device provided a significant high rectification ratio of 275 with a considerably low reverse saturation current of 0.2 nA. The optical transparency was about 80% for visible wavelengths, however showed an excellent blocking UV light. The nanostructured transparent heterojunction devices were applied for UV photodetectors to show ultra fast photoresponses with a rise time of 8.3 mS and a fall time of 20 ms, respectively. We suggest this transparent and super-performing UV responser can practically applied in transparent electronics and smart window applications.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.105-108
• /
• 2011

Newly-developed fabrication of a p-n heterojunction diode constructed with a p-Si nanowire (NW) and an n-ZnO nanoparticle (NP) thin-film by the dielectrophoresis (DEP) technique is demonstrated in this study. With the bias of 20 Vp-p at the input frequency of 1 MHz, the most efficient assembly of the n-ZnO NPs is shown for the fabrication of the p-n heterojunction diode with a p-Si NW. The p-n heterojunction diode fabricated in this study represents current rectifying characteristics with the turn on voltage of 1.1 V. The diode can be applied to the fabrication of optoelectrical devices such as photodetectors, light-emitting diodes (LEDs), or solar cells based on the high conductivity of the NW and the high surface to volume ratio of the NP thin film.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.7
• /
• pp.2200-2206
• /
• 2012

One-dimensional $TiO_2$ array grown on optically transparent electrode holds a promise as a photoelectrode for photoelectrochemical water splitting; however, its crystal structure is rutile, imposing constraints on the potent use of this nanostructure. To address this issue, a heterojunction with type-II band alignment was fabricated using atomic layer deposition (ALD) technique. One-dimensional core/shell structured $TiO_2$/ZnO heterojunction was superior to $TiO_2$ in the photoelectrochemical water splitting because of better charge separation and more favorable Fermi level. The heterojunction also possesses better light scattering property, which turned out to be beneficial even for improving the photoelectrochemical performance of semiconductor-sensitized solar cell.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.43.2-43.2
• /
• 2011

Minority Carrier recombination should be suppressed for high efficiency solar cells. However, impurities in the silicon bulk region deteriorate the minority carrier lifetimes, causes conversion efficiency drop. In this study, we introduced phosphorus external gettering for silicon heterojunction solar cell substrates. Gettering was undergone at 750, 800, 850 and $900^{\circ}C$ in furnace for 30 minutes. Bulk lifetimes and calculated diffusion length were improved. We applied phosphorus gettering to silicon heterojunction solar cells. Gettered group and ungettered group were used as substrate of silicon heterojunction solar cells. After fabrication, characteristics of solar cells were analyzed. The results were observed to see the enhancement of substrate quality which directly connects with solar cell properties.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.6 no.2
• /
• pp.119-123
• /
• 2006

This work presents the fabrication and characteristics of $Bi_2O_3/Si$ heterojunction prepared by rapid thermal oxidation technique without any postdeposition annealing condition. The bismuth trioxide film was deposited onto monocrystalline Si and glass substrates by rapid thermal oxidation of bismuth film with aid of halogen lamp at $500^{\circ}C/\;45$ s in static air. The structural, optical and electrical properties of $Bi_2O_3$ film were investigated and compared with other published results. The structural investigation showed that the grown films are polycrystalline and multiphase (${\alpha}-Bi_2O_3$ and ${\beta}-Bi_2O_3$). Optical properties revealed that these films having direct optical band gap of 2.55 eV at 300 K with high transparency in visible and NIR regions. Dark and illuminated I-V, CV, and spectral responsivity of $Bi_2O_3/Si$ heterojunction were investigated and discussed.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.491.2-491.2
• /
• 2014

Generally, silicon heterojunction solar cell has intrinsic and n-type of hydrogenated amorphous silicon (a-Si:H) as passivation layer and BSF layer. In this study, antimony, novel material, deposited on back side of the heterojunction solar cell as passivation and BSF layer to substitute the a-Si:H and the characteristics of the solar cell such electrical properties and optical properties were analyzed. And SIMS analysis was carried out to obtain the depth profile of the BSF layer which was deposited by laser annealing process.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.47.2-47.2
• /
• 2011

High-efficient transparent conductive oxide (TCO) film-embedding Si heterojunction solar cells were fabricated. An improved crystalline indium-tin-oxide (ITO) film was grown on an Al-doped ZnO (AZO) template upon hetero-epitaxial growth. This double TCO-layered Si solar cell provided significantly enhanced efficiency of 9.23 % as compared to the single TCO/Si devices. The effective arrangement of TCO films (ITO/AZO) provides a good interface, resulting in the enhanced photovoltaic performances. It discusses TCO film arrangement scheme for efficient TCO-layered heterojunction solar cells.