Focused light raises 2D semiconductor current up to 63-fold

May 28, 2026

Researchers developed a microlens based optical doping method called LAMP that raises 2D semiconductor transistor on-current by up to 63 times.

(Nanowerk News) Researchers at the Daegu Gyeongbuk Institute of Science and Technology (DGIST) have created a light based method for tuning the electrical behavior of 2D semiconductors with atomic precision. Led by Professor Hyuk-Jun Kwon, the team used finely focused laser light to raise the on-current of an ultrathin transistor by up to 63 times, a result that supports the use of 2D semiconductors in smaller, denser chips.

Key Findings

2D semiconductors are viewed as strong candidates for next-generation chips because they keep good electrical properties even when only a few atomic layers thick. That same thinness is also a weakness. With so little material present, defects and surface conditions strongly influence each layer, which makes the electrical properties engineers want difficult to reach reliably. Standard ways of tuning these properties by managing defects include high temperature heat treatment, plasma processing, and electron beam irradiation. Each of these can introduce damage or unwanted defects in regions that should be left untouched. The field has therefore needed a precise method that places defects only at chosen spots while keeping process temperatures low. The DGIST team answered this with Laser-Assisted Microlens Array Processing, or LAMP. The approach relies on self-assembled transparent polystyrene microparticles that act as tiny lenses. These microlenses focus a 532 nm continuous wave laser down to the sub-diffraction limit, the point at which light is squeezed tighter than an ordinary lens can normally achieve. The team used this concentrated light to form sulfur vacancies at selected points within a single layer of molybdenum disulfide (MoS₂). Schematic and characterization of the LAMP process. (a) Conceptual illustration of sulfur vacancy generation in monolayer MoS2 using LAMP with polystyrene microspheres (left: during LAMP processing, right: after removal of the microspheres). (b) COMSOL simulation of the enhanced electric field distribution transmitted through a 1.04 µm polystyrene microsphere under 532 nm laser illumination, demonstrating its microlens effect. (Image: DGIST) Sulfur vacancies are missing-atom defects that change how MoS₂ conducts electricity. By creating them at exact locations with light, the researchers produced stable n-type doping, meaning the material carries current through negatively charged electrons, without adding any chemical impurities. Because the microlenses concentrate the beam, the process needs less energy than direct laser irradiation, which lowers the risk of damage to the surrounding material. In testing, monolayer MoS₂ transistors treated with LAMP showed up to a 63-fold rise in on-current, a 51-fold gain in field-effect mobility, and a 37-fold increase in charge density compared with untreated devices. Field-effect mobility describes how quickly charge carriers move through the material, a core measure of transistor speed. The treated material was also non-volatile, holding its doping effect stably over a long period and confirming its potential for use in real semiconductor device processes. Professor Hyuk-Jun Kwon, of the Department of Electrical Engineering and Computer Science at DGIST, described the wider value of the work. “This research is significant for not only enhancing semiconductor properties but also in its design of a new defect control platform that precisely forms atomic-level defects at desired locations using only light. We expect it to be widely utilized as a key local doping technology in next-generation 2D semiconductor-based CMOS and future semiconductor processes.” The published results position LAMP as a local doping tool for 2D semiconductor based CMOS circuits and future three-dimensional semiconductor devices, where precise, low-damage defect placement matters. The study appeared in Small (“High‐Resolution Microlens‐Assisted Tunable n‐Type Optical Doping in Monolayer MoS2“).