Complete graphene film is prepared by depositing carbon atoms directly on Cu foils in a molecular beam epitaxy chamber at 300 °C. The Raman spectrum of the film has indicated that high-quality few-layer graphene is obtained. With back-gated transistor architecture, the characteristic current modulation of graphene transistors is observed. Following the similar growth procedure, graphitization is observed at room temperature, which is consistent with the molecular dynamics simulations of graphene growth.

The rapidly emerging requirement for device miniaturization and structural flexibility make 2D semiconductors and their van der Waals (vdWs) heterostructures extremely attractive for nonvolatile optoelectronic memory (NOM) applications. Although several concepts for 2D NOM have been demonstrated, multi‐heterojunction devices capable of further improving storage performance have received little attention. This work reports a concept for MoS2/black phosphorus (BP)/MoS2 multi‐heterojunction NOM with artificial trap sites through the BP oxidation, in which the trapped holes at BP/POx interface intrigue a persistent photoconductivity that hardly recovers within the experimental time scales (exceeding 104 s). As a result of the interfacial trap‐controlled charge injection, the device exhibits excellent photoresponsive memory characteristics, including a record high detectivity of ≈1.2 × 1016 Jones, a large light‐to‐dark switching ratio of ≈1.5 × 107, an ultralow off‐state current of ≈1.2 pA, and an outstanding multi‐bit storage capacity (11 storage states, 546 nC state–1). In addition, the middle BP layer in the multi‐heterojunction enables broadband spectrum distinction (375–1064 nm), together with a high polarization ratio of 8.4. The obtained results represent the significant step toward the high‐density integration of optoelectronic memories with 2D vdWs heterostructures.

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In this paper, GaSb nanostructures prepared under different Sb/background As ratios are investigated. With decreasing Sb/background As ratios, the morphologies of GaSb nanostructure changing from quantum dots (QDs) to quantum rings (QRs) are observed. The higher optical recombination probabilities of GaSb QRs are attributed to enhanced electron‐hole wave function overlapping and more surrounding electrons around the GaSb QR core shell. With well‐control Sb/background As ratios, the high‐temperature operation GaSb quantum‐dot infrared photodetector (QDIP) with simple stacked structure has been demonstrated. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper proposes a lossless data embedding method for Block Truncation Coding (BTC) compressed images based on prediction and histogram shifting techniques. Because BTC is easy to implement, and requires significantly less CPU cost, it has arouse widely attention in applications where real-time processing is demanded. For the existing lossless data embedding method in BTC codes, the decoder has to be specifically designed so that the spatial domain image can perfectly reconstructed from the compressed codes. Therefore, the application of these methods is limited. In the proposed embedding method, we slightly modified the quantization values of BCT codes to embed data losslessly, and a standard BTC decoder can be used to decode the BTC codes. The embedded secret messages can be extracted at the receiver side with the correct key. The experimental results revealed that the proposed method not only recovers the stego image to its original one, but also preserved a high image quality.