Recently, research teams from the University of Science and Technology of China, Huazhong University of Science and Technology, Shanghai Jiao Tong University, Peking University, and Xi'an University of Electronic Science and Technology have made significant progress in the field of integrated circuits, promoting the rapid development of China's integrated circuit industry.

China University of Science and Technology has made new progress in the research of maskless deep ultraviolet lithography technology

Recently, Sun Haiding, a special professor at the School of Microelectronics, University of Science and Technology of China, developed a three-dimensional vertically integrated deep ultraviolet light-emitting device array with self monitoring, self calibration, and adaptive capabilities for light energy. They have been successfully applied in a new type of maskless deep ultraviolet lithography technology.

This study proposes for the first time the application of deep ultraviolet micro LED arrays as light sources in maskless deep ultraviolet lithography technology. In addition to the widely used stepper lithography technology in integrated circuit chip manufacturing, this technology proposes to utilize the high energy density, high resolution, high integration, low energy consumption and other characteristics of each micro LED to provide a new path and method for achieving high-precision deep ultraviolet lithography. This research achievement is titled "Vertically Integrated Self Monitoring AlGaN Based Deep Ultraviolet Micro LED Array with Photodetector Via a Transparent Sapphire Substrate Towards Stable and Compact Maskless Photolithography Application" and was published in the important optical journal "Laser&Photonics Reviews".

Since the 1990s, low-cost, high-resolution maskless lithography technology has become one of the forefront hotspots in lithography research. However, the developed related technology patents are mainly concentrated in countries such as Europe, America, Japan, and South Korea, with high technical barriers. In this context, Professor Sun Haiding's iGaN team innovatively proposed and implemented a maskless deep ultraviolet lithography system based on a deep ultraviolet micro LED array as the light source. The team has systematically designed and optimized the epitaxial structure device size, sidewall morphology, and geometric shape of deep ultraviolet micro LEDs through years of research and accumulation in ultraviolet micro LEDs, greatly improving the luminous efficiency, luminous power, modulation bandwidth, and their multifunctionality and superior chip performance in sun blind ultraviolet detection, imaging, and sensing. They have successfully constructed an array system based on deep ultraviolet micro LEDs. Furthermore, by constructing an on-chip optoelectronic integrated chip that integrates light emission and detection, on-chip and inter chip optical communication system applications have been achieved.

In this study, the team utilized the advantages of ultra small size, ultra-high brightness, long lifespan, and low power consumption of deep ultraviolet micro LEDs to further develop a deep ultraviolet display optoelectronic integrated chip that integrates self-monitoring, self calibration, and adaptive functions, and applied it to a maskless deep ultraviolet lithography system, achieving international exploration of using this new ultraviolet light source for maskless lithography technology. Based on the pursuit of high efficiency and small-sized deep ultraviolet micro LEDs and their arrays, the team proposed a three-dimensional vertically integrated chip architecture that integrates deep ultraviolet micro LED array luminescence and photodetectors.

In this three-dimensional vertically integrated architecture, the ultraviolet photons emitted downwards by the deep ultraviolet micro LED array can pass through the transparent sapphire substrate and be captured by the ultraviolet detector on the back of the substrate, achieving "photon interconnection and integration" between the LED and the detector for efficient optical signal transmission. In addition, by building an external circuit feedback system, the team demonstrated the spontaneous stabilization and automatic calibration of the optical output energy density of deep ultraviolet micro LED arrays. Ultimately, the system can not only monitor the temporal fluctuations in the optical output energy density of array devices, but also continuously provide feedback signals to ensure constant optical output power and optical power density. The proposal of this high-power density, high stability, high integration, and low-power micro ultraviolet light source lays a solid foundation for the ultimate realization of compact, portable, and low-cost maskless deep ultraviolet lithography technology.

The research team of Huazhong University of Science and Technology has won honors for their achievements in the development of integrated computing chips for storage and computation

Recently, the latest research achievement of Professor Wang Chao's team of Huazhong University of Science and Technology in the field of integrated memory computing chips, "An Energy Efficient Low Voltage SRAM based Charge Recovery Logic Near Memory Computing Macro for Edge Computing", won the best conference paper at the 21st IEEE International Conference on Integrated Circuit Design and Technology in 2024

In the application of edge computing with limited energy, there are mainly two kinds of mainstream solutions of new AI computing chip with memory and computing integration, namely, in memory computing and near memory computing. In recent years, compared to in memory computing, near memory computing has attracted much attention due to its ability to more effectively implement more flexible and complex computing functions while improving integration; Compared to analog computing based on current domain, charge domain, and voltage domain, logic based digital computing has gradually become the mainstream technology for integrated storage and computation due to its high integration, accuracy, robustness, and reliability.

However, how to maintain high processing throughput and computational accuracy while reducing operating voltage, memory access frequency, and simplifying digital logic is an important research topic in the field of high-efficiency, low-power integrated computing. Therefore, this paper proposes a charge recovery logic near memory computing design scheme based on low-voltage static memory (SRAM) for deep neural network (DNN) convolution computation.

This design adopts a dual clock domain architecture, which reduces the access frequency of SRAM through weighted static data streams, lowers the power supply voltage and memory access frequency of SRAM, and significantly saves storage energy consumption; At the same time, a dual clock domain architecture is proposed to enable speed matching between Near Vth SRAM running in the slow clock domain and computing logic circuits in the fast clock domain; In addition, this design utilizes charge recovery logic to operate combinational logic circuits at sub Vth voltages, significantly reducing computational power consumption, and ensuring that computation speed is not affected through latch design and boost circuit.

This work implements the design of a near memory computing macrocell in a 40 nm CMOS process. The Sub Vth SRAM operates at a voltage of 0.6 V and a read/write frequency of 10 MHz. The Near Vth charge recovery logic circuit operates at 0.4 V and 1.1 V, with a clock frequency of 100 MHz, achieving a computational energy efficiency of 3.71 TOPS/W. The design specifications have reached the leading level in the international academic community. This work was conducted in collaboration with Professor Zheng Yuanjin's team at Nanyang Technological University in Singapore and was supported by the National Natural Science Foundation of China and the Technology Innovation Fund of the Innovation Research Institute of Huazhong University of Science and Technology.

It is reported that Professor Wang Chao from the Department of Microwave and Optoelectronic Integration at the School of Optoelectronics is the corresponding author of the paper, doctoral student Shen Zixuan and master's student Huang Lei are co first authors, and the School of Optoelectronics at Huazhong University of Science and Technology is the first completion unit of the paper.

Shanghai Jiao Tong University research team has made the latest breakthrough in semiconductor materials

Recently, the research group of Professor Zheng Yuanlin and Professor Chen Xianfeng from the School of Physics and Astronomy at Shanghai Jiao Tong University studied the enhanced optical parametric process in nonlinear crystal nanocavities. Through the Anapole resonance mechanism in thin film lithium niobate, the refractive index limitation of the material was overcome and the light intensity was localized within the nanocavity, achieving four orders of magnitude second harmonic enhancement.

The achievement was published in Nano Letters under the title "Enhanced Second Harmonic Generation in Thin Film Lithium Niobate Circular Bragg Nanoporosity".

Second order nonlinear effects can trigger many unique physical phenomena, such as the generation of second harmonics, which play an important role in basic science and various applications. The interaction process between light and matter at the micro nano scale, especially nonlinear parametric processes, relies on the strong nonlinearity of the material itself and requires the localization of light within a small mode volume to enhance the intensity of the interaction.

Among various materials, lithium niobate is currently one of the most widely used nonlinear crystals, which exhibits strong second-order nonlinear effects. However, the refractive index of lithium niobate is not very high, and its processing is also very difficult. The etched sidewalls are not steep enough, which limits its ability to confine the beam to the nanoscale and thus limits its application in nanophotonics.

The team utilized a circular Bragg ring grating (CBG) cavity on a nano thin film lithium niobate (TFLN) platform and designed Anapole resonance conditions inside the cavity center disk to confine light within 1.5 wavelength diameters, ultimately achieving significant enhancement of nonlinear effects. The CBG structure is widely used in lasers, quantum emitters, and nonlinear devices due to its high light collection efficiency and vertical surface emission. Anapole resonance is an ideal choice for enhancing the interaction between light and matter at sub wavelength scales due to the destructive interference of oscillating electric dipole moment and annular dipole moment far-field radiation modes without far-field radiation. In this study, the team experimentally achieved Anapole resonance enhanced second harmonic generation in CBG on X-cut thin film lithium niobate. The normalized conversion efficiency reaches 1.21 × 10 ^ -2 cm ^ 2/GW at a pump intensity of 1.9 MW/cm ^ 2; Compared to thin film lithium niobate, the enhancement factor reaches 42000 times.

In addition, the team also studied the characteristics of second harmonic generation in elliptical Bragg ring grating (EBG) cavities and achieved polarization independent second harmonic generation of s/p incident light without reducing nonlinear conversion efficiency (about 10 ^ -2 cm ^ 2/GW).

Peking University Shenzhen Graduate School has made significant progress in the field of high-performance, low dimensional flexible electronic integration

Recently, Professor Zhang Shengdong's research group from the School of Information Engineering at Shenzhen Graduate School published a research paper titled "Hydrogen bonding integrated low dimensional flexible electronics beyond the limits of van der Waals contacts" in the internationally renowned journal Advanced Materials, in the form of Frontier Highlight Recommendation. This work innovatively introduces non covalent hydrogen bonding interactions to overcome the high contact resistance caused by inherent van der Waals gaps, providing a scalable solution for achieving high-performance, low-power flexible electronic devices beyond van der Waals contact limitations.

Realizing low contact resistance is a fundamental prerequisite for developing high-performance electronic devices, but it remains a daunting challenge in the field of low dimensional semiconductors. One of the challenges in achieving low contact resistance is the requirement for band alignment between metals and semiconductors, as well as a contact interface with no Fermi level pinning, in order to minimize Schottky barriers to the greatest extent possible. By using non covalent van der Waals forces instead of covalent bonds to bond metals with low dimensional semiconductors, a clean and non-destructive atomic interface can be formed, enabling the customization of Schottky barriers to approach the Schottky Mott limit.

However, due to the limitations of weak coupling of electronic states caused by additional tunnel barriers and inherent van der Waals gaps, it is still rare to experimentally achieve van der Waals contacts with ultra-low contact resistance. This restriction has sparked a revolution in contact technology, represented by semi metallic contacts such as bismuth Bi and antimony Sb.

However, semi metallic contacts are limited by high deposition temperatures and narrow work function ranges. For the field of flexible electronics, the situation has become even worse as it requires comprehensive consideration of the compatibility of flexible manufacturing processes and materials, as well as the trade-off between mechanical and electrical properties. Both flexible and rigid electronic devices urgently need to develop a more universal approach to fundamentally overcome the limitations of van der Waals integration.

Adjusting the fundamental interaction between metal and semiconductor contacts is the essential way to overcome high contact resistance. This study revealed through first principles calculations that compared to van der Waals forces, hydrogen bonding can significantly enhance the tunneling effect of electrons and does not introduce metal induced gap states. It is expected to achieve contact resistance approaching the quantum limit, providing a universal approach to overcome the limitations of van der Waals integration while maintaining a clean contact interface. By utilizing the low-temperature full solution method, the author achieved π - hydrogen bonding contact for the first time in surface engineered MXene/carbon nanotube gold half heterojunctions, and based on this, high-performance flexible thin film transistors were realized.

This work jointly characterized the evidence of hydrogen bonding in gold half contacts through temperature dependent FTIR and electrical measurements, and elucidated the basic physical mechanism of the anomalous phenomenon of temperature dependent tunneling resistance, ultimately achieving a hydrogen bonding contact resistance value one order of magnitude lower than the corresponding van der Waals contact. Hydrogen bonded integrated transistors not only have ultra-high flexibility and can withstand more than 100000 bends with a bending radius as low as 1.5mm, but also have a carrier mobility one order of magnitude higher than the corresponding van der Waals transistors, providing a scalable solution for achieving high-performance, low-power flexible electronic devices beyond van der Waals contact limitations.

This work was independently completed by teachers and students from the School of Information Engineering. Doctoral student Liu Dedong was the first author of the paper, master's student Liu Ziyi was the co first author of the paper, and Zhang Min was the corresponding author of the paper. Zhang Shengdong, as well as master's students Gao Xinyu, Zhu Jiahao, Wang Zifan, Qiu Rui, Ren Qinqi, and Zhang Yiming, are co authors. The above research has received support from the National Key Research and Development Program, the General Project of the National Natural Science Foundation of China, the Basic Research Project of the Shenzhen Science and Technology Innovation Committee, and the Shenzhen Supercomputing Center.

Academician Hao Yue and Professor Chang Jingjing from Xidian University have published important scientific research results in top international journals

Recently, Professor Chang Jingjing's team from Xi'an University of Electronic Science and Technology proposed a strategy of directly introducing fluoride ions with strong electronegativity into the halide perovskite lattice to suppress the migration of perovskite ions and stabilize the crystal phase. This method significantly improves the performance and stability of perovskite photovoltaic devices. This achievement was published in Angewandte Chemie International Edition, titled Prohibiting Ion Migration and Stabilizing Crystal Phase in Halide Perovskite via Directly Incorporated Fluoride Anion. The only corresponding unit of the article is Xi'an University of Electronic Science and Technology, and the corresponding authors are Professor Chang Jingjing and Dr. Hu Zhaosheng from the team.

Ionic migration and poor stability are key factors that lead to performance degradation of commonly used perovskite devices and limit their practical applications. Currently, the modification of F - with strong electronegativity on the surface, grain boundaries, or interfaces of perovskite films to enhance material stability and device performance has become a research hotspot. Although such modification strategies have shown significant potential in improving the performance of perovskite materials, there have been no reports on direct doping into the lattice of perovskite thin films. It is of great significance to explore the direct introduction of perovskite lattice by doping to regulate the characteristics of perovskite semiconductors. However, fluoride has lower solubility compared to other halides, making it very challenging to introduce F - into the lattice through solution methods.

In this study, the author developed a novel class of volatile solubilizing ligands - pyridine halides - to assist in the dissolution of PbF2. This innovative technology enables fluoride ions (F -) to directly integrate into the perovskite lattice. The research results found that due to the large difference in ionic radius between F - and commonly used halide ions (such as I - and Br -) in perovskite, F - tends to occupy the interstitial positions of CsPbI2Br in perovskite rather than forming an octahedral skeleton structure. This discovery provides a new approach for the introduction of F -. In addition, this method has certain universality, not only applicable to all inorganic perovskite materials, but also to organic-inorganic hybrid perovskite systems. This achievement not only provides new strategies for optimizing the performance of perovskite materials, but also offers possibilities for promoting the development of perovskite optoelectronic devices and other application fields, with important scientific and practical value.