Thanks for all your contributions to discussion, data analyzing, measurements, as well as suggestions. Finally, I would like to thank my parents for their encouragement, support, and everlasting love.

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Plasma damage of low-k dielectrics during photoresist (PR) stripping in a dual-damascene process is a critical issue in the application of copper/low-k technology for ⩽45nm nodes to increase the signal processing speed of integrated circuit devices. In this article, a detailed and systematic work has been conducted to study the low-k damage on porous methyl silsesquioxane ultralow-k films using various PR strip chemistries and process conditions on a high density plasma reactor. The experimental results obtained from different test methodologies show that the low-k damage generated under fixed process conditions increases in the order of NH3<N2<H2∕N2<H2<O2. Among plasma control parameters, bias power has a very pronounced effect on low-k damage for reducing chemistries due to the acceleration of Si–C bond breaking by ion bombardment. Source power also affects the low-k damage significantly as it controls the ion density and flux to the wafer surface. The pressure effect is more complicated and shows different characteristics for oxidizing and reducing chemistries. The extent of low-k damage depends on the orientation of the wafer surface exposed to the plasma, leading to different sensitivity of the damage to the strip chemistry and process condition. Based on this work, an optimized chemistry and process regime are identified to effectively reduce low-k damage and achieve good strip process performance.

Graphene-based van der Waals heterostructures are promising building blocks for broadband photodetection because of the gapless nature of graphene. However, their performance is mostly limited by the inevitable trade-off between low dark current and photocurrent generation. Here, we demonstrate a hybrid photodetection mode based on the photogating effect coupled with the photovoltaic effect via tunable quantum tunneling through the unique graphene/Bi 2 Se 3 heterointerface. The tunneling junction formed between the semimetallic graphene and the topologically insulating Bi 2 Se 3 exhibits asymmetric rectifying and hysteretic current–voltage characteristics, which significantly suppresses the dark current and enhances the photocurrent. The photocurrent-to-dark current ratio increases by about a factor of 10 with the electrical tuning of tunneling resistance for efficient light detection covering the major photonic spectral band from the visible to the mid-infrared ranges. Our findings provide a novel concept of using tunable quantum tunneling for highly sensitive broadband photodetection in mixed-dimensional van der Waals heterostructures.

Articles you may be interested inStudy on the oxidation and reduction of tungsten surface for sub-50nm patterning process J. Vac. Sci. Technol. A 30, 061305 (2012); 10.1116/1.4758790 Effect of Cu contamination on recombination of O atoms on a plasma-oxidized silicon surfaceThe surface oxidation of tungsten is a serious issue in plasma processing of advanced integrated-circuit devices where tungsten is being used as a gate electrode. In this article, we study tungsten oxidation in O 2 / H 2 / N 2 downstream plasma at a temperature ഛ300°C. The results show that oxidation occurs rapidly in O 2 downstream plasma to form stable WO 3 . However, oxidation can be reduced effectively by adding H 2 and totally suppressed when H 2 concentration in the gas feed reaches a certain low level at which the plasma is still oxygen dominant. Tungsten oxidation increases significantly with sample temperature and exposure time in O 2 downstream plasma. However, H 2 addition reduces both temperature and time dependences due to the coexistence and competition of oxidation and reduction processes. When N 2 is also added, the efficiency of H 2 in O 2 downstream plasma in controlling tungsten oxidation is lowered. The findings may provide effective approaches to various applications of selective oxidation over tungsten, such as photoresist stripping and polysilicon oxidation on tungsten gate structures.

We report a single- and dual-wavelength switchable mode-locked dissipative soliton in an ytterbium-doped fiber laser based on graphene/WS2 nanocomposites saturable absorber. The graphene/WS2 nanocomposites film possesses efficient saturable absorption characteristics with large modulation depth (45.1%), which results in the stable single-wavelength mode-locking operation with pulse duration of 450 ps. By carefully rotating the polarization controller, the mode-locking operation can be switched to a dual-wavelength at both 1066.4 nm and 1069.2 nm due to the modulation of the intracavity birefringence. Our work extends the studies for 2D nanomaterials and supplies potential applications in the multi-wavelength fiber laser.

We report a new method for obtaining a stable single-frequency Yb-doped fiber laser by introducing a graphene film into a fiber loop mirror combined with a simple linear cavity. The graphene film acts as a saturable absorber so as to form a dynamic absorbing grating in the 3 dB fiber loop. This grating is like a narrow-band filter for discriminating and selecting longitudinal modes. Moreover, we use a polarization controller in the linear resonator to suppress the spatial hole burning effect. The maximum output power is 16 mW at 1 064 nm with a pump power of 110 mW at 975 nm, the slope efficiency is 15%, and the SNR is about 60 dB. To the best of our knowledge, this is the first demonstration of a 1 064 nm single-frequency laser based on a linear cavity with a graphene-loop mirror filter.

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