Lithography is one of the most widely used methods for cutting‐edge research and industrial applications, mainly owing to its ability to draw patterns in the micro and even nanoscale. However, the fabrication of semiconductor micro/nanostructures via conventional electron or optical lithography technologies often requires a time‐consuming multistep process and the use of expensive facilities. Herein, a low‐cost, high‐resolution, facile, and versatile direct patterning method based on metal–organic molecular precursors is reported. The ink‐based metal–organic precursors are found to operate as negative resists, with the material exposed by different methods (electron‐beam/laser/heat/ultraviolet (UV)) to render them insoluble in the development process. This technical process can deliver metal chalcogenide semiconductors with arbitrary 2D/3D patterns with sub‐50 nm resolution. Electron beam lithography, two‐photon absorption lithography, thermal scanning probe lithography, and UV photolithography are demonstrated for the direct patterning process. Different metal chalcogenide semiconductor nanodevices, such as photoconductive selenium‐doped Sb2S3 nanoribbons, p‐type PbS single‐nanowire field‐effect transistors, and p‐n junction CdS/Cu2S nanowire solar cells, are fabricated by this method. This direct patterning technique is a versatile and simple micro/nanolithography technology with considerable potential for “lab‐on‐a‐chip” preparation of semiconductor devices.
We have adapted the Keldysh multiphoton absorption theory to one-photon transitions in semiconductors. We find that the Keldysh theory is in good agreement with both the absolute values and with the frequency dependence of the absorption coefficients of InSb and GaAs. We have also reexamined the often used firstorder perturbation approach and derived an expression for the absorption coefficient using the k. p method.A comparison between theory and experimental data has been carried out without adjustable parameters.
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