According to foreign media reports, scientists from the US Naval Research Laboratory (NRL) have discovered a new way to passivate the next generation of single-layer optical material defects to improve optical quality and achieve single-layer LEDs and other optical components. miniaturization.

This laser processing technology developed by NRL scientists can greatly improve the optical properties of single-layer molybdenum disulfide (MoS2), which is also a high-spatial direct gap semiconductor; this process can laser The light emission efficiency of the material of the beam writing region is increased by 200 times. The resulting passivation layer is stable in air and vacuum.

Saujan Sivaram, one of the researchers, said: "From a chemical point of view, we have discovered a new photocatalytic reaction using lasers and water molecules; from a general perspective, this work can be of high quality and Optically active atomic thin materials are integrated into a variety of applications such as electronics, electrocatalysts, memory and quantum computing applications."

Sivaram pointed out that due to its high light absorption and direct band gap characteristics, atomic-scale thin transition metal disulfide compounds (TMD), such as molybdenum disulfide (MoS2), for flexible devices, solar cells and photoelectric sensors, etc. Great use. “These semiconductor materials are especially advantageous for applications where weight and flexibility are important,” he says. Unfortunately, their optical properties are often extremely variable and non-uniform, thus improving and controlling these TMD materials. Optical properties are becoming very important to achieve reliable and efficient devices. Defects often destroy the luminescence of these single-layer semiconductors. These defects are non-radiative, producing heat rather than light, so removing or passivating these defects is toward An important step in high-efficiency optoelectronic devices."

In a conventional LED, about 90% is a heat sink for improving the cooling effect. After the defect is reduced, smaller devices will consume less power, making the distributed sensor and low-power electronics longer.

Passivation by water molecules

Researchers have shown that water molecules can passivate MoS2 only when exposed to lasers with energies above the TMD bandgap. The result is an increase in photoluminescence without spectral shift. The treated area maintains a strong light emission compared to the area that has been passivated by water molecules. This also shows that the chemical reaction between the environmental gas molecules and MoS2 is caused by the laser.