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738 results on '"Ye, Jichun"'

6. Directional carrier transport in micrometer-thick gallium oxide films for high-performance deep-ultraviolet photodetection

Author

Zhang, Wenrui, Wang, Wei, Zhang, Jinfu, Zhang, Tan, Chen, Li, Wang, Liu, Zhang, Yu, Cao, Yanwei, Ji, Li, and Ye, Jichun

Subjects
Condensed Matter - Materials Science
Abstract

Incorporating emerging ultrawide bandgap semiconductors with a metal-semiconductor-metal (MSM) architecture is highly desired for deep-ultraviolet (DUV) photodetection. However, synthesis-induced defects in semiconductors complicate the rational design of MSM DUV photodetectors due to their dual role as carrier donors and trap centers, leading to a commonly observed trade-off between responsivity and response time. Here, we demonstrate a simultaneous improvement of these two parameters in {\epsilon}-Ga2O3 MSM photodetectors by establishing a low-defect diffusion barrier for directional carrier transport. Specifically, using a micrometer thickness far exceeding its effective light absorption depth, the {\epsilon}-Ga2O3 MSM photodetector achieves over 18-fold enhancement of responsivity and simultaneous reduction of the response time, which exhibits a state-of-the-art photo-to-dark current ratio near 10^8, a superior responsivity of >1300 A/W, an ultrahigh detectivity of >10^16 Jones and a decay time of 123 ms. Combined depth-profile spectroscopic and microscopic analysis reveals the existence of a broad defective region near the lattice-mismatched interface followed by a more defect-free dark region, while the latter one serves as a diffusion barrier to assist frontward carrier transport for substantially enhancing the photodetector performance. This work reveals the critical role of the semiconductor defect profile in tuning carrier transport for fabricating high-performance MSM DUV photodetectors.

Published
2022
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36. Top-Down Dual-Interface Carrier Management for Highly Efficient and Stable Perovskite/Silicon Tandem Solar Cells.

Author

Li, Xin, Ying, Zhiqin, Li, Shuo, Chen, Lei, Zhang, Meili, Liu, Linhui, Guo, Xuchao, Wu, Jun, Sun, Yihan, Xiao, Chuanxiao, Zeng, Yuheng, Wu, Jian, Yang, Xi, and Ye, Jichun

Subjects
SILICON solar cells, SOLAR cells, SILICON surfaces, ENERGY bands, PEROVSKITE
Abstract

Highlights: An innovated top-down dual-interface carrier management strategy is developed to effectively improve both interfaces of the wide-bandgap perovskite using a multi-functionalized piperazinium chloride post-treatment. The 1.68 eV unencapsulated single-junction perovskite solar cells exhibit a champion PCE of 22.3%, with a record VOC × FF product (84.4% relative to the Shockley–Queisser limit). An impressive PCE of 31.5% for the 1.04 cm2 monolithic perovskite/silicon tandem solar cell based on silicon heterojunction bottom cell is demonstrated. Despite significant advancements in the power conversion efficiency (PCE) of perovskite/silicon tandem solar cells, improving carrier management in top cells remains challenging due to the defective dual interfaces of wide-bandgap perovskite, particularly on textured silicon surfaces. Herein, a series of halide ions (Cl−, Br−, I−) substituted piperazinium salts are designed and synthesized as post-treatment modifiers for perovskite surfaces. Notably, piperazinium chloride induces an asymmetric bidirectional ions distribution from the top to the bottom surface, with large piperazinium cations concentrating at the perovskite surface and small chloride anions migrating downward to accumulate at the buried interface. This results in effective dual-interface defect passivation and energy band modulation, enabling wide-bandgap (1.68 eV) perovskite solar cells to achieve a PCE of 22.3% and a record product of open-circuit voltage × fill factor (84.4% relative to the Shockley–Queisser limit). Furthermore, the device retains 91.3% of its initial efficiency after 1200 h of maximum power point tracking without encapsulation. When integrated with double-textured silicon heterojunction solar cells, a remarkable PCE of 31.5% is achieved for a 1.04 cm2 monolithic perovskite/silicon tandem solar cell, exhibiting excellent long-term operational stability (T80 = 755 h) without encapsulation in ambient air. This work provides a convenient strategy on dual-interface engineering for making high-efficiency and stable perovskite platforms. [ABSTRACT FROM AUTHOR]

Published
2025
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37. Al2O3/in situ GaON gate dielectrics incorporated GaN MIS-HEMTs with stable VTH and significantly reduced interface state density.

Author

Luo, Tian, Chen, Sitong, Li, Ji, Ye, Fang, Yu, Zhehan, Xu, Wei, Ye, Jichun, and Guo, Wei

Subjects
LATTICE constants, THRESHOLD voltage, DENSITY of states, INTERFACE stability, GALLIUM nitride
Abstract

This work reports a metal–insulator–semiconductor High-Electron-Mobility-Transistor (HEMT) with Al2O3/in situ GaON bi-layer gate dielectric for improved threshold voltage (VTH) stability and reduced interface state density. With a combination of in situ GaON and large bandgap Al2O3 on top of the recessed gate region, normally-off HEMT was achieved with high On/Off current (ION/IOFF) ratio of 109, low VTH hysteresis less than 60 mV, and low-interface trap density (Dit) in the range of 4 × 1011–2 × 1012 cm−2·eV−1. Thanks to the sharp GaN/oxide interface with narrow distribution of lattice constant, uniform strain distribution and significantly reduced trap density were obtained. More importantly, our proposed bi-layer gate dielectric is perfectly compatible with the conventionally utilized gate recessing technique compared to the conventionally utilized in situ SiNx, demonstrating itself as a promising candidate in GaN power devices. [ABSTRACT FROM AUTHOR]

Published
2025
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41. Enhanced Passivation Effect of Tunnel Oxide Prepared by Ozone‐Gas Oxidation (OGO) for n‐Type Polysilicon Passivated Contact (TOPCon) Solar Cells.

Author

Yang, Lei, Ou, Yali, Lv, Xiang, Lin, Na, Zeng, Yuheng, Hu, Zechen, Yuan, Shuai, Ye, Jichun, Yu, Xuegong, and Yang, Deren

Subjects
SILICON solar cells, SOLAR cell manufacturing, PHOTOELECTRON spectroscopy, SILICON oxide, SOLAR cells
Abstract

Nowadays, a stack of heavily doped polysilicon (poly‐Si) and tunnel oxide (SiOx) is widely employed to improve the passivation performance in n‐type tunnel oxide passivated contact (TOPCon) silicon solar cells. In this case, it is critical to develop an in‐line advanced fabrication process capable of producing high‐quality tunnel SiOx. Herein, an in‐line ozone‐gas oxidation (OGO) process to prepare the tunnel SiOx is proposed to be applied in n‐type TOPCon solar cell fabrication, which has obtained better performance compared with previously reported in‐line plasma‐assisted N2O oxidation (PANO) process. In order to explore the underlying mechanism, the electrical properties of the OGO and PANO tunnel SiOx are analyzed by deep‐level transient spectroscopy technology. Notably, continuous interface states in the band gap are detected for OGO tunnel SiOx, with the interface state densities (Dit) of 1.2 × 1012–3.6 × 1012 cm−2 eV−1 distributed in Ev + (0.15–0.40) eV, which is significantly lower than PANO tunnel SiOx. Furthermore, X‐ray photoelectron spectroscopy analysis indicate that the percentage of SiO2 (Si4+) in OGO tunnel SiOx is higher than which in PANO tunnel SiOx. Therefore, we ascribe the lower Dit to the good inhibitory effects on the formation of low‐valent silicon oxides during the OGO process. In a nutshell, OGO tunnel SiOx has a great potential to be applied in n‐type TOPCon silicon solar cell, which may be available for global photovoltaics industry. [ABSTRACT FROM AUTHOR]

Published
2025
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45. Temperature and Humidity Stable Alkali/Alkaline‐Earth Metal Carbonates as Electron Heterocontacts for Silicon Photovoltaics

Author

Wan, Yimao, Bullock, James, Hettick, Mark, Xu, Zhaoran, Samundsett, Chris, Yan, Di, Peng, Jun, Ye, Jichun, Javey, Ali, and Cuevas, Andres

Subjects
alkali carbonate, alkaline earth metal carbonates, electron heterocontacts, silicon photovoltaics, Macromolecular and Materials Chemistry, Materials Engineering, Interdisciplinary Engineering
Abstract

Nanometer scale interfacial layers between the metal cathode and the n-type semiconductor play a critical role in enhancing the transport of charge carriers in and out of optoelectronic devices. Here, a range of nanoscale alkali and alkaline earth metal carbonates (i.e., potassium, rubidium, caesium, calcium, strontium, and barium) are shown to function effectively as electron heterocontacts to lightly doped n-type crystalline silicon (c-Si), which is particularly challenging to contact with common metals. These carbonate interlayers are shown to enhance the performance of n-type c-Si proof-of-concept solar cells up to a power conversion efficiency of ≈19%. Furthermore, these devices are thermally stable up to 350 °C and both the caesium and barium carbonates pass a standard 1000 h damp heat test, with >95% of their initial performance maintained. The temperature and humidity stable electron heterocontacts based on alkali and alkaline earth metal carbonates show a high potential for industrial feasibility and longevity for deployment in the field.

Published
2018

50. Ultrawide Bandgap Diamond/ε-Ga2O3Heterojunction pn Diodes with Breakdown Voltages over 3 kV

Author

Zhang, Jianguo, Liu, Ningtao, Chen, Li, Yang, Xun, Guo, Haizhong, Wang, Zefeng, Yuan, Ming-Qian, Yan, Xue-Jun, Yang, Jianqun, Li, Xingji, Shan, Chongxin, Ye, Jichun, and Zhang, Wenrui

Abstract

Robust bipolar devices based on exclusively ultrawide bandgap (UWBG) semiconductors are highly desired for advanced power electronics. The heterojunction strategy has been a prevailing method for fabricating a bipolar device due to the lack of effective bipolar doping in the same UWBG material. Here, we demonstrate a unique heterojunction design integrating the p-type diamond and n-type ε-Ga2O3that achieves remarkable breakdown voltages surpassing 3000 V. Despite the lattice mismatch, the heteroepitaxial ε-Ga2O3film is established on the diamond substrate, forming an atomically sharp interface with C–O–Ga bonding and enabling the O-terminated diamond surface for constructing an effective rectifying heterojunction. The ultra-high-quality interface, together with the lightly doped diamond as the drift layer, largely weakens the commonly met electric field crowding effect in power diodes and provides a cost-effective thermal management route. This study provides an efficient heterojunction design to realize the potential of UWBG semiconductors for ultra-high-power applications.

Published
2025
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