Characterization of tunnel oxide passivated contact with n-type poly-Si on ptype c-Si wafer substrate

Xueqi Guo,Yuheng Zeng,Zhi Zhang,Yuqing Huang,Mingdun Liao,Qing Yang,Zhixue Wang,Minyong Du,Denggao Guan,Baojie Yan,Jichun Ye 한국물리학회 2019 Current Applied Physics Vol.19 No.7

The junction properties of tunnel silicon oxide (SiOx) passivated contact (TOPCon) with n-type poly-Si on p-type c-Si wafer are characterized using current-voltage (J-V) and capacitance-voltage (C-V) measurements. The dark J-V curves show a standard diode characteristic with a turn-on voltage of ∼0.63 V, indicating a p-n junction is formed. While the C-V curve displays an irregular shape with features of 1) a slow C increase with the decrease of the magnitude of reverse bias voltage, being used to estimate the built-in potential (Vbi), 2) a significant increase at a given positive bias voltage, corresponding to the geometric capacitance crossing the ultrathin SiOx, and 3) a sharp decrease to negative values, resulting from the charge tunneling through the SiOx layer. The C of depleting layer deviates from the normal linear curve in the 1/C2-V plot, which is caused by the diffusion of P dopants from the n-type poly-Si into the p-type c-Si wafer as confirmed by the electrochemical capacitance-voltage measurements. However, the 1/C2+γ-V plots with γ > 0 leads to linear curves with a proper γ and the Vbi can still be estimated. We find that the Vbi is the range of 0.75–0.85 V, increases with the increase of the doping ratio during the poly-Si fabrication process, and correlates with the passivation quality as measured by the reverse saturated current and implied open circuit voltage extracted from transient photoconductivity decay.

Diagentic features of illite in Upper Triassic Chang-7 tight oil sandstones, Ordos Basin

Ai Wang,Dakang Zhong,Haihua Zhu,Lele Guo,Yangjinfeng Jiang,Xueqi Yang,Rui Xie 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.2

The Upper Triassic Chang-7 tight oil sandstones are the main tight clastic reservoirs in the Ordos Basin, central China. Illite is one of the most important cements affecting porosity and permeability of the tight oil sandstones, and this study focuses on different types of illitization and its relative formation time. The Chang-7 tight sandstones are mainly fine-grained lithic arkose and feldspar lithic sandstones, rich in mica and illite (hydrous mica). They are formed in distal delta front to semi-deep and deep lake facies, mainly deposited in a low energy environment. Porosity and permeability are very low (average porosity 8.58% and permeability 0.20 mD). The illite has many morphological characteristics and is multiphase, incorporating six types of illitization: hydrous mica, mica, and smectite illitization at the eodiagenetic stage, and kaolinite and K-feldspar illitization, and neoformation illite particles, at the mesodiagenetic stage. These different types of illitization are mainly controlled by sedimentary environment and provenance. Quartz overgrowth and diagenetic illites appear to be locally mutually exclusive, competing for detrital grain surfaces, but neoformation illite particles appear to form on the quartz overgrowth. The systematic study of Upper Triassic Chang-7 tight oil sandstones carried out here, enhances our understanding of illitization and the diagenetic model of the Ordos Basin, and contributes to reducing the exploration risk of continental tight sandstone reservoirs.

Depositional and diagenetic controls on the reservoir quality of Upper Triassic Chang-7 tight oil sandstones, southwestern Ordos basin, China

Ai Wang,Dakang Zhong,Haihua Zhu,Lele Guo,Zhuopei Li,Yangjinfeng Jiang,Xueqi Yang,Rui Xie,Xiaowei Zheng 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.3

The seventh oil layer of the Upper Triassic Yanchang Formation (Chang-7) tight oil sandstone reservoirs is a major exploration target. A significant amount of hydrocarbons has been discovered in these reservoirs in the southwestern Ordos basin in China. The Chang-7 tight sandstones are characterised as tight with low porosity, low permeability, and strong heterogeneity. This study investigates the sedimentary facies, diagenesis, and their impact on the reservoir quality of the Chang-7 tight oil sandstones. The sandstones were deposited in a deltaic-lacustrine depositional system. Three major depositional facies are identified consisting of delta front fed by braided rivers and meandering rivers, and slump turbidite fans. The depositional environment exerts a key control on reservoir quality. The distinct low-energy sedimentary environment produced fine to very fine-grained sandstones with high matrix and mica contents, characterised by low initial porosity and permeability. Diagenesis mainly comprised mechanical compaction and cementation by quartz, carbonate minerals and various clay minerals. The reservoir properties of the Chang-7 sandstones are generally poor, with porosity of 1.4–20.7% (average porosity 8.6%) and permeability of 0.001–116.7 mD (average 0.2 mD), which are attributed to significant compaction and cementation. Mechanical compaction was more important than cementation for reducing porosity, whereas secondary dissolution porosity was significant for the Chang-7 tight oil sandstones due to closer proximity to the underlying Chang-73 source rocks.

Allyl isothiocyanate may reverse the expression of MRP1 in COPD rats via the Notch1 signaling pathway

Jie Wu,Xueqi Wang,Zhaomin Yao,Qingqing Wu,Wei Fang,Zegeng Li,Dianlei Wang 대한약학회 2019 Archives of Pharmacal Research Vol.42 No.11

In the present study, the roles of AITC in upregulatingthe MRP1 expression and its relationship with theactivation of the Notch1 signaling pathway were investigatedby combining the in vivo and in vitro experiments. AITCwas administered to the COPD model rats and normal ratsto explore the association between Notch1 and MRP1. Thehuman bronchial epithelial cells were treated with DAPT,the Notch1 signaling pathway inhibitor, to verify the effectof Notch1 on the expression of AITC-induced MRP1. Comparedwith the control group, the expressions of Notch1,Hes1 (the target gene of Notch1) and MRP1 in the lung tissueof the COPD model group were significantly inhibited. In contrast to the COPD model group, the expressions ofMRP1, Hes1 and Notch1 dramatically up-regulated followingthe treatment with Low/High doses of AITC. The expressionof MRP1 in the 16 HBE cells was down-regulated bythe inhibition of Notch in a DAPT concentration-dependentmanner. Additionally, the AITC-induced up-regulation ofthe MRP1 expression was markedly impaired following the inhibition of Notch1. The above results indicated that thepulmonary function and the expression of MRP1 in COPDrats could be improved by AITC, which was partly dependenton the Notch1 signaling pathway. Therefore, targetingthe Notch signaling pathway may present as an effectivetherapeutic strategy for COPD treatment.

High vis-light photocatalytic property of g-C3N4 on four pollutants (RhB, MB, TC-HCl and P-Nitrophenol)

Lian Xiaoxue,Li Yan,Zou Yunling,An Dongmin,Wang Qiong,Zhou Qingjun,Li Xueqi 한국물리학회 2022 Current Applied Physics Vol.39 No.-

The g-C3N4 nanosheets were synthesized by a multistage program calcination with different heating rate, which was an easy, low-cost, and quick method. The morphology and structure of samples were characterized by various techniques. The performance evaluation of the samples was tested by degrading Rhodamine B, Methylene Blue, Tetracycline Hydrochloride and P-Nitrophenol in visible light. The results show that the photodegradation properties of TP-g-C3N4 prepared by multistage program calcination are the best than others. In particular, the degradation rate of TP-g-C3N4 to Rhodamine B reached 99.6% in just 4 min. TP-g-C3N4 catalyst has excellent stability and recycling performance. According to free radical capture experiments, •O2- may be the main active species for pollutant degradation. The possible photocatalytic degradation mechanism was also discussed. Due to the high specific surface area and a narrow band gap, the TP-g-C3N4 becomes a promising photocatalyst.