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Atomically thin two-dimensional (2D) materials exhibit extraordinary optical, electrical, and mechanical properties. Many functional nanostructures and devices of exceptional performance based on 2D materials have been demonstrated. However, the processing of 2D materials remains challenging due to inadequacies that are mainly driven by high fabrication cost, complex steps, and inefficient impurity control. On the other hand, laser-aided processing techniques offer versatility, nanoscale precision, and high throughput. Numerous efforts have showcased the implementation of laser processing and functionalization of 2D materials to control their physical properties and optimize device functionality. In this Perspective, we summarize research progress on laser-enabled thinning, patterning, doping, and functionalization of 2D materials. Continuing advances in optical processing techniques are anticipated to further accelerate the deployment of 2D materials and devices in many fields, including photonics, optoelectronics, and sensor applications. 

We demonstrate the laser mediated atomic layer etching (ALEt) of silicon. Using a nanosecond pulsed 266 nm laser focused loosely over and in a parallel configuration to the surface of the silicon, we dissociate Cl2 gas to induce chlorination. Then, we use pulsed picosecond irradiation to remove the chlorinated layer. Subsequently, we perform continuous wave (CW) laser annealing to eliminate amorphization caused by the picosecond laser etching. Based on atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), we observed strong evidence of chlorination and digital etching at 0.85 nm etching per cycle with good uniformity. 

Chemical doping can be used to control the charge-carrier polarity and concentration in two-dimensional van der Waals materials. However, conventional methods based on substitutional doping or surface functionalization result in the degradation of electrical mobility due to structural disorder, and the maximum doping density is set by the solubility limit of dopants. Here we show that a reversible laser-assisted chlorination process can be used to create high doping concentrations (above 3 × 1013 cm−2) in graphene monolayers with minimal drops in mobility. The approach uses two lasers—with distinct photon energies and geometric configurations—that are designed for chlorination and subsequent chlorine removal, allowing highly doped patterns to be written and erased without damaging the graphene. To illustrate the capabilities of our approach, we use it to create rewritable photoactive junctions for graphene-based photodetectors.