• Korean Journal of Materials Research
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• v.25 no.9
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• pp.487-491
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• 2015

In photovoltaic power generation where minority carrier generation via light absorption is competing against minority carrier recombination, the substrate thickness and material quality are interdependent, and appropriate combination of the two variables is important in obtaining the maximum output power generation. Medici, a two-dimensional semiconductor device simulation tool, is used to investigate the interdependency in relation to the maximum power output in front-lit Si solar cells. Qualitatively, the results indicate that a high quality substrate must be thick and that a low quality substrate must be thin in order to achieve the maximum power generation in the respective materials. The dividing point is $70{\mu}m/5{\times}10^{-6}sec$. That is, for materials with a minority carrier recombination lifetime longer than $5{\times}10^{-6}sec$, the substrate must be thicker than $70{\mu}m$, while for materials with a lifetime shorter than $5{\times}10^{-6}sec$, the substrate must be thinner than $70{\mu}m$. In substrate fabrication, the thinner the wafer, the lower the cost of material, but the higher the cost of wafer fabrication. Thus, the optimum thickness/lifetime combinations are defined in this study along with the substrate cost considerations as part of the factors to be considered in material selection.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.22-25
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• 2002

In this paper, we deposited MgO buffer layer on p-type (100)Si substrate in the condition of substrate temperature 400$^{\circ}C$, working gas ratio Ar:O$_2$=80:20, RF Power 50W, working pressure 10mtorr, and the thickness of the film was about 300${\AA}$. Then we deposited Ba$\sub$0.5/Sr$\sub$0.5/TiO$_3$ thin film using RF Magnetron sputtering method on the MgO/Si substrate in various RF power of 25W, 50W, 75W. The film deposited in 50W showed the best crystalline from the XRD measurement. To know the electrical properties of the film, we manufactured Al/BSTMgO(300${\AA}$)/Si/Al structure capacitor. In the result of I-V measurement, The leakage current density of the capacitor was lower than 10$\^$-7/A/$\textrm{cm}^2$ at the range of ${\pm}$150kV/cm. From C-V characteristics of the capacitor, can calculate the dielectric constant and it was 305. Finally we deposited BST thin film on bare Si substrate and (100)MgO substrate in the same deposition condition. From the comparate of the properties of these samples, we found the properties of BST thin film which deposited on MgO/Si substrate were better than on bare Si substrate and similar to on MgO substrate.

• Transactions on Electrical and Electronic Materials
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• v.5 no.4
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• pp.153-157
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• 2004

ITO thin films were deposited on PET and soda-lime glass substrates by a dc reactive magnetron sputtering of In-Sn alloy metal target without substrate heater and post-deposition thermal treatment. The dependency of rf-bias voltage and substrate power during deposition processing was investigated to control the electrical and optical properties of ITO films. The range of rf bias voltage is from 0 to -80 V and the substrate power is applied from 10 to 50 W. The minimum resistivity of ITO film is 5.4${\times}$10$^{-4}$ $\Omega$cm at 50 W power and rf-bias voltage of -20 V. The best transmittance of ITO films at 550 nm wavelength is 91 % in the substrate power of 30 W and rf-bias voltage of -80 V.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.387-392
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• 2018

Static characteristics of SiC (silicon carbide) lateral p-i-n diodes implemented on semi-insulating substrate without an epitaxial layer are inVestigated. On-axis SiC HPSI (high purity semi-insulating) and VDSI (Vanadium doped semi-insulating) substrates are used to fabricate the lateral p-i-n diode. The space between anode and cathode ($L_{AC}$) is Varied from 5 to $20{\mu}m$ to inVestigate the effect of intrinsic-region length on static characteristics. Maximum breakdown Voltages of HPSI and VDSI are 1117 and 841 V at $L_{AC}=20{\mu}m$, respectiVely. Due to the doped Vanadium ions in VDSI substrate, diffusion length of carriers in the VDSI substrate is less than that of the HPSI substrate. A forward Voltage drop of the diode implemented on VDSI substrate is 12 V at the forward current of $1{\mu}A$, which is higher than 2.5 V of the diode implemented on HPSI substrate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.826-831
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• 2009

In this paper, a high power RF amplifier module using AlN substrate of high thermal conductivity has been proposed. This RF amplifier module has the advantage of compact size and effective heat dissipation for the packaging of high power chip. To fabricate the thru-hole and scribing line on AlN substrate, the key parameters of $CO_2$ laser were experimented. And then, microstrip lines and spiral planar inductors were fabricated on an AlN substrate using the thin-film process. The fabricated microstrip lines on the AlN substrate has an attenuation value of 0.1 dB/mm up to 10 GHz. The fabricated spiral planar inductor has a high quality factor, a maximum of about 62 at 1 GHz for a 5.65 nH inductor. Packaging of a RF power amplifier was implemented on an AlN substrate with thru-hole. From the measured results, the gain is 24 dB from 13 to 15 GHz and the output power is 33.65 dBm(2.3 W).

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1421-1423
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• 1996

In this study, the effect of solar cell cover glass on the solar cell performance is evaluated. Silicon solar cell (active area:4*6cm, efficiency:12.6% at AMO condition) is used for this study. ITO(Indium tin Oxide) film thickness of the ITO/AR/substrate glass/solar cell structure samples are $40{\AA}$, $60{\AA}$, $160{\AA}$, $240{\AA}$ respectively. The solar cell maximum output power on the stacking structure variations showed 465mW in the AR/ITO/substrate glass/solar cell, and minimum output power showed 403mW in the AR/substrate glass/solar cell. The maximum output power of the solar cell on the ITO thickness variations of the ITO/AR/substrate glass/solar cell showed 460mW at $40{\AA}$ then decrease output power as ITO thickness increase. For environment tests, all samples are exposed UV light in the vacuum chanber. The output power degradation of AR(UVR)/substrate glass/solar cell stacking structure is small compared with ITO/AR(UVR)/substrate glass/solar cell stacking structure.

• Korean Journal of Materials Research
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• v.22 no.9
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• pp.450-453
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• 2012

In crystalline solar cells, the substrate itself constitutes a large portion of the fabrication cost as it is derived from semiconductor ingots grown in costly high temperature processes. Thinner wafer substrates allow some cost saving as more wafers can be sliced from a given ingot, although technological limitations in slicing or sawing of wafers off an ingot, as well as the physical strength of the sliced wafers, put a lower limit on the substrate thickness. Complementary to these economical and techno-physical points of view, a device operation point of view of the substrate thickness would be useful. With this in mind, BC-BJ Si and GaAs solar cells are compared one to one by means of the Medici device simulation, with a particular emphasis on the substrate thickness. Under ideal conditions of 0.6 ${\mu}m$ photons entering the 10 ${\mu}m$-wide BC-BJ solar cells at the normal incident angle (${\theta}=90^{\circ}$), GaAs is about 2.3 times more efficient than Si in terms of peak cell power output: 42.3 $mW{\cdot}cm^{-2}$ vs. 18.2 $mW{\cdot}cm^{-2}$. This strong performance of GaAs, though only under ideal conditions, gives a strong indication that this material could stand competitively against Si, despite its known high material and process costs. Within the limitation of the minority carrier recombination lifetime value of $5{\times}10^{-5}$ sec used in the device simulation, the solar cell power is known to be only weakly dependent on the substrate thickness, particularly under about 100 ${\mu}m$, for both Si and GaAs. Though the optimum substrate thickness is about 100 ${\mu}m$ or less, the reduction in the power output is less than 10% from the peak values even when the substrate thickness is increased to 190 ${\mu}m$. Thus, for crystalline Si and GaAs with a relatively long recombination lifetime, extra efforts to be spent on thinning the substrate should be weighed against the expected actual gain in the solar cell output power.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.107-112
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• 2017

The BCBJ (Back Contact and Back Junction) or back-lit solar cell design eliminates shading loss by placing the pn junction and metal electrode contacts all on one side that faces away from the sun. However, as the electron-hole generation sites now are located very far from the pn junction, loss by minority-carrier recombination can be a significant issue. Utilizing Medici, a 2-dimensional semiconductor device simulation tool, the interdependency between the substrate thickness and the minority-carrier recombination lifetime was studied in terms of how these factors affect the solar cell power output. Qualitatively speaking, the results indicate that a very high quality substrate with a long recombination lifetime is needed to maintain the maximum power generation. The quantitative value of the recombination lifetime of minority-carriers, i.e., electrons in p-type substrates, required in the BCBJ cell is about one order of magnitude longer than that in the front-lit cell, i.e., $5{\times}10^{-4}sec$ vs. $5{\times}10^{-5}sec$. Regardless of substrate thickness up to $150{\mu}m$, the power output in the BCBJ cell stays at nearly the maximum value of about $1.8{\times}10^{-2}W{\cdot}cm^{-2}$, or $18mW{\cdot}cm^{-2}$, as long as the recombination lifetime is $5{\times}10^{-4}s$ or longer. The output power, however, declines steeply to as low as $10mW{\cdot}cm^{-2}$ when the recombination lifetime becomes significantly shorter than $5{\times}10^{-4}sec$. Substrate thinning is found to be not as effective as in the front-lit case in stemming the decline in the output power. In view of these results, for BCBJ applications, the substrate needs to be only mono-crystalline Si of very high quality. This bars the use of poly-crystalline Si, which is gaining wider acceptance in standard front-lit solar cells.

• Electrical & Electronic Materials
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• v.9 no.2
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• pp.196-203
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• 1996

The highly c-axis oriented zinc oxide thin films were deposited on Sapphire(0001) substrates by reactive RF magnetron sputtering. The characteristics of zinc oxide thin films on RF power, substrate-target distance, and substrate temperature were investigated by XRD, SEM and EDX analyses. The physical characteristics of zinc oxide thin films changed with various deposition conditions. The higher substrate temperatures were, The better crystallinity of zinc oxide thin films. The highly c-axis oriented zinc oxide thin films were obtained at sputter pressure 5mTorr, rf power 200W, substrate temperature 350.deg. C, substrate-target distance 5.5cm. In these conditions, the resistivity of zinc oxide thin films deposited on pt/sapphire was 12.196*10$^{9}$ [.ohm.cm].

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.113-118
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• 2011

According to the high accuracy of semiconductor equipments, PCB substrate with much thin thickness is required. However, it is very difficult to sustain the PCB substrate without deformation in case of horizontal installation, due to low bending stiffness. In this research, new PCB process equipment with vertical installation has been developed in order to solve the problem of PCB substrate damage during etching process. As the main parts of etching system on PCB substrate, PCB substrate and JIG are analyzed through finite element method and experimental test. Through the analysis results of stress state, we could find the optimal JIG design to make the damage as low as possible.