ORCID Profile
0000-0001-5536-8388
Current Organisations
UNSW Sydney
,
Zhejiang University
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Publisher: Springer Science and Business Media LLC
Date: 28-03-2018
Publisher: Elsevier BV
Date: 06-2023
Publisher: IOP Publishing
Date: 08-06-2023
Abstract: Silicon carbide (SiC) is a typical wide band-gap semiconductor material that exhibits excellent physical properties such as high electron saturated drift velocity, high breakdown field, etc. The SiC material contains many polytypes, among which 4H-SiC is almost the most popular polytype as it possesses a suitable band-gap and high electron saturated drift velocity. In order to produce 4H-SiC power devices with a high barrier voltage of over several thousand volts, the minority carrier lifetime of 4H-SiC single crystals must be carefully managed. In general, both bulk defects and surface defects in 4H-SiC can reduce the minority carrier lifetime. Nevertheless, as surface defects have received less attention in publications, this study reviews surface defects in 4H-SiC. These defects can be classified into a number of categories, such as triangle defect, pit, carrot, etc. This paper discusses each one in idually followed by the introduction of industrially feasible methods to characterize them. Following this, the impact of surface defects on the minority carrier lifetime is analyzed and discussed. Finally, a particular emphasis is put on discussing various passivation schemes and their effects on the minority carrier lifetime of 4H-SiC single crystals. Overall, this review paper aims to help young researchers comprehend surface defects in 4H-SiC single crystal material.
Publisher: MDPI AG
Date: 11-01-2020
DOI: 10.3390/IJMS21020468
Abstract: In the first trimester of pregnancy, placental development involves a wide range of cellular processes. These include trophoblast proliferation, fusion, and differentiation, which are dependent on tight cell cycle control. The intrauterine environment affects placental development, which also includes the trophoblast cell cycle. In this work, we focus on maternal obesity to assess whether an altered intrauterine milieu modulates expression and protein levels of placental cell cycle regulators in early human pregnancy. For this purpose, we use first trimester placental tissue from lean and obese women (gestational week 5+0–11+6, n = 58). Using a PCR panel, a cell cycle protein array, and STRING database analysis, we identify a network of cell cycle regulators increased by maternal obesity in which breast cancer 1 (BRCA1) is a central player. Immunostaining localizes BRCA1 predominantly to the villous and the extravillous cytotrophoblast. Obesity-driven BRCA1 upregulation is not able to be explained by DNA methylation (EPIC array) or by short-term treatment of chorionic villous explants at 2.5% oxygen with tumor necrosis factor α (TNF-α) (50 mg/mL), leptin (100 mg/mL), interleukin 6 (IL-6) (100 mg/mL), or high glucose (25 nM). Oxygen tension rises during the first trimester, but this change in vitro has no effect on BRCA1 (2.5% and 6.5% O2). We conclude that maternal obesity affects placental cell cycle regulation and speculate this may alter placental development.
Publisher: Elsevier BV
Date: 07-2021
Publisher: AIP Publishing
Date: 09-10-2017
DOI: 10.1063/1.5001117
Abstract: Silicon surface is one of the dominant recombination sites for silicon solar cells. Generally, the recombination ability of silicon surface is characterized in terms of surface recombination velocity. However, silicon surface actually contain a series of donor and acceptor levels across the silicon band gap, and therefore the surface recombination velocity is too general to provide detailed information of the silicon surface states. In this paper, we used the measured transient capacitance data to extract the detailed information (like defect energy levels, defect densities, and capture cross sections) of the silicon surface states. Furthermore, the influence of copper contamination on silicon surface states was examined, and it was found that copper contamination can change the localized energy levels of “clean” silicon surface states to the band-like energy levels, meanwhile the defect densities and capture cross sections were both enlarged.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 06-2023
Publisher: Elsevier BV
Date: 11-2010
Publisher: Elsevier BV
Date: 09-2021
Publisher: Wiley
Date: 22-04-2021
Abstract: Herein, the degradation and regeneration processes of p‐type cast‐monosilicon passivated emitter rear contact solar cells are investigated, by taking open‐circuit voltage as a measure for the light‐ and elevated‐temperature‐induced degradation (LeTID) and regeneration extent. Degradation and regeneration are triggered by current injection and light soaking at the same temperatures. Then, an Arrhenius plot, derived from the proposed model, is used to extract the degradation and regeneration rate constants of LeTID during both current injection and light‐soaking processes. The activation energies of degradation processes are calculated to be (0.790 ± 0.064) and (0.828 ± 0.013) eV for current injection and light soaking, respectively. The corresponding activation energies for regeneration processes are (1.059 ± 0.112) and (1.179 ± 0.070) eV, respectively. Notably, the similar activation energies indicate that the root cause of the LeTID induced by current injection or light soaking is the same. In addition, an exponential dependence of the rate constants upon the injection current values during the whole degradation and regeneration cycle induced by current injection is observed. These results are not only significant for understanding the kinetics of LeTID but also can shed light on effective LeTID suppression method in the photovoltaic industry.
Publisher: AIP Publishing
Date: 08-2011
DOI: 10.1063/1.3616145
Abstract: We have investigated the effect of a thin interfacial silicon oxide on the atomic-layer-deposited Al2O3 film passivating the silicon surface based on rapid thermal process (RTP). It is found that the effective carrier lifetime of s les strongly depends on the RTP temperature and reaches the maximum value at 550 °C. Both capacitance-voltage measurements and theoretical simulation have revealed that the RTP treatment cannot only modulate the charges in the Al2O3 film but also reduce the density of interface states responsible for the surface recombination. These results are interesting for the fabrication of high efficiency silicon solar cells in photovoltaics.
Publisher: Elsevier BV
Date: 06-2017
Publisher: MDPI AG
Date: 12-10-2021
Abstract: Type 1 diabetes mellitus (T1DM) is associated with reduced fetal growth in early pregnancy, but a contributing role of the placenta has remained elusive. Thus, we investigated whether T1DM alters placental development in the first trimester. Using a protein array, the level of 60 cell-cycle-related proteins was determined in human first trimester placental tissue (gestational week 5–11) from control (n = 11) and T1DM pregnancies (n = 12). Primary trophoblasts (gestational week 7–12, n = 32) were incubated in the absence (control) or presence of hyperglycemia (25 mM D-glucose) and hyperosmolarity (5.5 mM D-glucose + 19.5 mM D-mannitol). We quantified the number of viable and dead trophoblasts (CASY Counter) and assessed cell cycle distribution (FACS) and trophoblast invasion using a transwell assay. T1DM was associated with a significant (p 0.05) downregulation of Ki67 (−26%), chk1 (−25%), and p73 (−26%). The number of viable trophoblasts was reduced under hyperglycemia (−23%) and hyperosmolarity (−18%), whereas trophoblast invasion was increased only under hyperglycemia (+6%). Trophoblast cell death and cell cycle distribution remained unaffected. Collectively, our data demonstrate that hyperglycemia decreases trophoblast proliferation as a potential contributing factor to the reduced placental growth in T1DM in vivo.
Publisher: Elsevier BV
Date: 04-2019
Publisher: Springer Science and Business Media LLC
Date: 25-04-2018
Publisher: Wiley
Date: 24-11-2020
DOI: 10.1002/PIP.3364
Publisher: Wiley
Date: 17-04-2018
Publisher: Elsevier BV
Date: 12-2015
Publisher: AIP Publishing
Date: 24-05-2010
DOI: 10.1063/1.3431580
Abstract: Interfacial dislocation networks were formed in silicon by direct bonding technology. Cathodoluminescence and deep level transient spectroscopy measurements verified that the D1 luminescence at 1.5 μm is associated with carrier transitions via a dislocation-related deep level at 0.35 eV. Both the experiment and theoretical calculations demonstrate that application of an external bias voltage on the bonding interface increases the majority carrier density at this deep level, thereby enhancing the local dislocation-related luminescence. However, beyond a critical voltage, corresponding to saturation of the majority carrier occupancy, the luminescence intensity decreases, due to the reduction in minority carrier density.
Publisher: AIP Publishing
Date: 10-2019
DOI: 10.1063/1.5122253
Abstract: Hydrogen is identified as a useful technique to passivate defects within crystalline silicon. However, the effect of hydrogen passivation for a silicon surface is normally characterized as a reduction in surface recombination velocity (SRV), which is not enough to reflect the detailed changes of electronic properties, such as defect density, defect energy levels, and capture cross section, of silicon surface states. In this paper, we utilized the transient capacitance measurement to characterize the detailed electronic properties of silicon surface states before and after hydrogenation. The differences, in terms of the effects of hydrogenation on silicon surface states, either in copper contaminated conditions or clean conditions, are presented and discussed.
Publisher: IOP Publishing
Date: 11-07-2016
Publisher: Elsevier BV
Date: 05-2016
Publisher: IOP Publishing
Date: 22-09-2022
Abstract: Crystalline silicon solar cells are always moving towards ‘high efficiency and low cost’, which requires continuously improving the quality of crystalline silicon materials. Nevertheless, crystalline silicon materials typically contain various kinds of impurities and defects, which act as carrier recombination centers. Therefore these impurities and defects must be well controlled during the solar cell fabrication processes to improve the cell efficiency. Hydrogenation of crystalline silicon is one important method to deactivate these impurities and defects, which is so-called ‘hydrogenation engineering’ in this paper. Hydrogen is widely reported to be able to passivate erse defects like crystallographic defects, metallic impurities, boron-oxygen related defects and etc, but the effectiveness of hydrogen passivation depends strongly on the processing conditions. Moreover, in this decade, advanced hydrogenation technique has been developed and widely applied in the photovoltaic industry to significantly improve the performance of silicon solar cells. As the research on hydrogenation study has made a significant progress, it is the right time to write a review paper on introducing the state-of-the-art hydrogenation study and its applications in photovoltaic industry. The paper first introduces the fundamental properties of hydrogen in crystalline silicon and then discusses the applications of hydrogen on deactivating/inducing typical defects (e.g. dislocations, grain boundaries, various metallic impurities, boron–oxygen related defects and light and elevated temperature induced degradation defect) in p- and n-type crystalline silicon, respectively. At last, the benefits of hydrogenation engineering on the next-generation silicon solar cells (e.g. tunnel oxide passivated contact (TOPCon) and silicon heterojunction (SHJ) solar cells) are discussed. Overall, it was found that hydrogen can deactivate most of typical defects (sometimes induce defect) in n- and p-type crystalline silicon, leading to a significant efficiency enhancement in passivated emitter rear contact, TOPCon and SHJ solar cells. In conclusion, the paper aims to assist young researchers to better understand hydrogenation research.
Publisher: Springer Science and Business Media LLC
Date: 10-2016
No related grants have been discovered for Lihui Song.