• Title/Summary/Keyword: minority carrier lifetime

Search Result 90, Processing Time 0.025 seconds

Evaluation of Mechanical Backside Damage of Silicon Wafer by Minority Carrier Recombination Lifetime and Photo-Acoustic Displacement Method

  • Park, Chi-Young;Cho, Sang-Hee
    • Proceedings of the Korea Association of Crystal Growth Conference
    • /
    • 1997.10a
    • /
    • pp.155-159
    • /
    • 1997
  • We investigated the effect of mechanical backside damage in Czochralski silicon wafer. The intensity of mechanical damage were evaluated by minority carrier recombination lifetime by a laser excitation/microwave reflection photoconductance decay method, photo-acoustic displacement method, X-ray section topography, and wet oxidation/preferential etch methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the photoacoustic displacement values are also increased proportionally.

  • PDF

Effect of mechanical backside damage upon minority carrier recombination lifetime measurement by laser/microwave photoconductance technique (기계적 후면 손상이 레이저/극초단파 광전도 기법에 의한 소수 반송자 재결합 수명 측정에 미치는 영향)

  • 조상희;최치영;조기현
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.5 no.4
    • /
    • pp.408-413
    • /
    • 1995
  • We investigated the effect of mechanical backside damage upon minority carrier recombination lifetime measurement in Czochralski silicon substrate by laser excitation/microwave reflection photoconductance decay method. The intensity of mechanical damage was evaluated by X-ray double crystal rocking curve, X-ray section topography and wet oxidation/preferential etch methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the threshold full width at half maximum value which affect minority carrier lifetime measurement is about 13 secs.

  • PDF

A Simulated Study of Silicon Solar Cell Power Output as a Function of Minority-Carrier Recombination Lifetime and Substrate Thickness

  • Choe, Kwang Su
    • Korean Journal of Materials Research
    • /
    • v.25 no.9
    • /
    • pp.487-491
    • /
    • 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.

Relationships between Carrier Lifetime and Surface Roughness in Silicon Wafer by Mechanical Damage (기계적 손상에 의한 실리콘 웨이퍼의 반송자 수명과 표면 거칠기와의 관계)

  • 최치영;조상희
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.12 no.1
    • /
    • pp.27-34
    • /
    • 1999
  • We investigated the effect of mechanical back side damage in viewpoint of electrical and surface morphological characteristics in Czochralski silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductance decay technique, atomic force microscope, optical microscope, wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage degree, the lower the minority carrier lifetime, and surface roughness, damage depth and density of oxidation induced stacking fault increased proportionally.

  • PDF

The Gettering Effect of Boron Doped n-type Monocrystalline Silicon Wafer by In-situ Wet and Dry Oxidation

  • Jo, Yeong-Jun;Yun, Ji-Su;Jang, Hyo-Sik
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2012.08a
    • /
    • pp.429-429
    • /
    • 2012
  • To investigate the gettering effect of B-doped n-type monocrystalline silicon wafer, we made the p-n junction by diffusing boron into n-type monocrystalline Si substrate and then oxidized the boron doped n-type monocrystalline silicon wafer by in-situ wet and dry oxidation. After oxidation, the minority carrier lifetime was measured by using microwave photoconductance and the sheet resistance by 4-point probe, respectively. The junction depth was analyzed by Secondary Ion Mass Spectrometry (SIMS). Boron diffusion reduced the metal impurities in the bulk of silicon wafer and increased the minority carrier lifetime. In the case of wet oxidation, the sheet resistance value of ${\sim}46{\Omega}/{\Box}$ was obtained at $900^{\circ}C$, depostion time 50 min, and drive-in time 10 min. Uniformity was ~7% at $925^{\circ}C$, deposition time 30 min, and drive-in time 10 min. Finally, the minority carrier lifetime was shown to be increased from $3.3{\mu}s$ for bare wafer to $21.6{\mu}s$ for $900^{\circ}C$, deposition 40 min, and drive-in 10 min condition. In the case of dry oxidation, for the condition of 50 min deposition, 10 min drive-in, and O2 flow of 2000 SCCM, the minority carrier lifetime of 16.3us, the sheet resistance of ${\sim}48{\Omega}/{\Box}$, and uniformity of 2% were measured.

  • PDF

Simulated Study on the Effects of Substrate Thickness and Minority-Carrier Lifetime in Back Contact and Back Junction Si Solar Cells

  • Choe, Kwang Su
    • Korean Journal of Materials Research
    • /
    • v.27 no.2
    • /
    • pp.107-112
    • /
    • 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.

Determination of Minority Carrier Lifetime in Solar Cells by the Method of Photoelectric Frequency Modulation (광전 주파수 변조방법에 의한 태양전지의 소수 반송자 수명 측정)

  • 박우상;정호선
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.20 no.4
    • /
    • pp.30-35
    • /
    • 1983
  • Numerical calculations have been made about the phase differences of the short circuit current in a solar cell according to the variation of the modulation frequency. The phase differences in short circuit current of the solar cell exposed to the modulated light source is measured experimentally. From the above two results, the minority carrier lifetime has been determined. Also, minority carrier lifetime has been determined from the observed photo-induced open circuit voltage decay wave form that follows termination of the excitation.

  • PDF

Effects of the Local Lifetime Control on the Switching and Latch-up Characteristics of IGBT (Local Lifetime Control이 TGBT의 스위칭 및 래치업 특성에 미치는 영향)

  • Lee, Se-Kyu;Chung, Sang-Koo
    • Proceedings of the KIEE Conference
    • /
    • 1999.07d
    • /
    • pp.1953-1955
    • /
    • 1999
  • The effects of the local lifetime control on the characteristics of IGBT are investigated using the 2-dimensional device simulator, MEDICI. Many lumped resistive turn-off simulations are carried out to analyze the effects of the minority carrier lifetime, the width, and the position of the region with a reduced local minority carrier lifetime. As a result of these simulations, it is concluded that the on state voltage drop$(V_{CE,SAT})$ is only slightly increased while the switching behavior is greatly improved if the low lifetime region is properly set. And these results are compared with IGBTs having uniform lifetime.

  • PDF

Study on the Passivation of Si Surface by Incorporation of Nitrogen in Al2O3 Thin Films Grown by Atomic Layer Deposition (원자층 증착법으로 형성된 Al2O3 박막의 질소 도핑에 따른 실리콘 표면의 부동화 특성 연구)

  • Hong, Hee Kyeung;Heo, Jaeyeong
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.22 no.4
    • /
    • pp.111-115
    • /
    • 2015
  • To improve the efficiency of the Si solar cell, high minority carrier life time is required. Therefore, the passivation technology is important to eliminate point defects on the silicon surface, causing the loss of minority carrier recombination. PECVD or post-annealing of thermally-grown $SiO_2$ is commonly used to form the passivation layer, but a high-temperature process and low thermal stability is a critical factor of low minority carrier lifetime. In this study, atomic layer deposition was used to grow the $Al_2O_3$ passivation layer at low temperature process. $Al_2O_3$ was selected as a passivation layer which has a low surface recombination velocity because of the fixed charge density. For the high charge density, an improved minority carrier lifetime, and a low surface recombination, nitrogen was doped in the $Al_2O_3$ thin film and the improvement of passivation was studied.

Estimation of mechanical damage by minority carrier recombination lifetime and near surface micro defect in silicon wafer (실리콘 웨이퍼에서 소수 반송자 재결합 수명과 표면 부위 미세 결함에 의한 기계적 손상 평가)

  • 최치영;조상희
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.9 no.2
    • /
    • pp.157-161
    • /
    • 1999
  • We investigated the effect of mechanical back side damage in Czochralski silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductance decay ($\mu$-PCD) technique, wet oxidation/preferential etching methods, near surface micro defect (NSMD) analysis, and X-ray section topography. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and NSMD density increased proportionally, also correlated to the oxidation induced stacking fault (OISF) density. Thus, NSMD technique can be used separately from conventional etching method in OISF measurement.

  • PDF