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Kinetic effects of plasma-dielectric interaction are studied theoretically with respect to the mechanisms of electron extraction from solids in response to ion and electron bombardment, coupled with plasma dynamics of a weakly emissive sheath. Emission coefficients of incident beams are first calculated by quantum mechanical as well as semi-classical approaches involving Auger neutralization, energy-dependent ejection due to primary beam, and reflection of lowenergy electrons, which are then incorporated into a 1D1V simulation and plasma kinetic theory. Presheath with sheath structures are derived using fluid and kinetic theory regarding ion-induced emission, respectively. The Bohm criterion considering surface emission is evaluated as well. For electron-induced emission, it is found that sheath potential is no longer collinear with plasma electron temperature in our integrated model. Additionally, reflection of low-energy electrons is justified to have a minor impact on the floating sheath for low temperature half-bounded plasma under low pressure. The combined effects of both incident ions and electrons in bounded plasma are analyzed with symmetrical/asymmetrical emission yields at two boundaries. It is then proved that wall potential is barely affected by bulk plasma influx if emission coefficients are symmetrical, while emission due to transiting beam can drastically modify the sheath solution. Electron reflection also becomes more influential if secondary electrons have low initial energy. Finally, we summarize different roles of ion and electron in sheath structure. It is shown that ioninduced emission mitigates sheath potential but cannot reach critical emission on contrast to that of electron flux.

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Memory plays a vital role in modern information society. High‐speed and low‐power nonvolatile memory is urgently demanded in the era of big data. However, ultrafast nonvolatile memory with nanosecond‐timescale operation speed and long‐term retention is still unavailable. Herein, an ultrafast nonvolatile memory based on van der Waals heterostructure is proposed, where a charge‐trapping material, graphdiyne (GDY), serves as the charge‐trapping layer. With the band‐engineered heterostructure and excellent charge‐trapping capability of GDY, charges are directly injected into the GDY layer and are persistently captured by the trapping sites in GDY, which result in an ultrafast writing speed (8 ns), a low operation voltage (30 mV), and a long retention time (over 104 s). Moreover, a high on/off ratio of 106 is demonstrated by this memory, which enables the achievement of multibit storage with 6 discrete storage levels. This device fills the blank of ultrafast nonvolatile memory technology, which makes it a promising candidate for next‐generation high‐speed and low‐power‐consumption nonvolatile memory.

Residual charges and species created by previous streamers have a great impact on the characteristics of the next discharge. This is especially pronounced in repetitively pulsed discharges, where the physical and chemical reactions during the decay phase play a very important role. We have performed double-pulse streamer experiments in artificial air and pure nitrogen with a varying pulse delay (Δt) from 0.45 μs to 20 ms. We have observed morphological transformations of the 2nd-pulse streamer as a function of Δt and classified six typical stages by streamer length. The propagation distance of the 2nd-pulse streamer can be 66% longer than the 1st-pulse in 66.7 mbar nitrogen, while it is 37% longer in air under the same conditions. However, we find that the longer propagation distance of the 2nd-pulse streamer in N 2 is not caused by a higher velocity nor by fast gas heating of previous channels under our experimental conditions, but by earlier inception which gives more time to propagate during the pulse. In air, on the other hand, the streamers initiate almost at the same time in both pulses but the inception cloud of the 2nd-pulse streamer breaks up earlier. The onset of every stage occurs at smaller Δt in air than in N 2 at the same pressure. These observations imply that different mechanisms work in N 2 and air, e.g. photoionization and attachment.