高脈衝UV雷射直寫網印石墨烯薄膜於電極成型之探討

Investigation of Electrode Forming of Screen-printed Graphene Films by Using High Pulsed Ultraviolet Laser Direct Writing

曾釋鋒(Shih-Feng Tseng) ； 蕭文澤(Wen-Tse Hsiao) ； 張天立(Tien-Li Chang)

《科儀新知》 214期 (2018/03) Pp. 67-81

摘要

本研究以高脈衝奈秒紫外光(ultraviolet, UV)雷射直寫搭配影像拼接技術(stitching technologies)，應用於石墨烯(graphene)薄膜沈積在玻璃基板之電極成型與雷射加工參數交互作用探討。石墨烯薄膜剝蝕機制採雷射加工參數調控，包括雷射脈衝能量密度、雷射脈衝重複頻率和振鏡掃描速度。此外，雷射脈衝重複頻率和振鏡掃描速度可用於計算光斑重疊率和討論電極成型之品質。實驗最後使用三維共焦顯微鏡和掃描式電子顯微鏡量測雷射電極成型後之絕緣線表面形貌、邊緣品質、三維形貌之絕緣線輪廓和電極結構；半導體參數分析儀量測電極雷射成型前後之薄膜I-V曲線特性，並討論不同雷射能量密度對電特性的影響。實驗結果顯示：UV雷射能量密度從0.62 J/cm^2至2.43 J/cm^2時，絕緣線寬度從27.3 μm增加至34.2 μm，絕緣線深度也從1.53 μm微幅增至2.14 μm。此外，當XY振鏡掃描速度為2200 mm/s降至200 mm/s時，絕緣線寬度從6.2 μm增加至9.9 μm，絕緣線深度也從2.2 μm微幅增至3.5 μm。當UV雷射能量密度設定為3.027 J/cm^2情況下直寫網印石墨烯薄膜，其石墨烯薄膜之I-V曲線圖在任何電壓下，其輸出之電流均為零，應證此能量密度足以將剝蝕通道之兩側電極絕緣。

並列摘要

This study aims to develop the laser direct writing (LDW) and image stitching technologies by using an ultraviolet (UV) laser processing system for the electrode forming and to investigate the interaction between laser beams and graphene thin films coated on glass substrates. The laser processing parameters including the laser pulse fluence, the pulse repetition frequency, and the scanning speed of galvanometers were adjusted to ablate out the graphene thin films. The laser pulse repetition frequency and the scanning speed of galvanometers could apply to calculate the overlapping rate of laser spot and to discuss the surface quality of electrode forming. The surface morphology, edge quality, three-dimensional topography, and profile of isolated lines and electrode structures after laser forming were measured by a confocal laser scanning microscope and a scanning electron microscope (SEM). Moreover, a semiconductor parameter analyzer was used to measure the I-V curve before and after laser forming on film surfaces and also to discuss the electrical property at different laser fluences. The experimental results revealed that the UV laser fluences increased from 0.62 J/cm2 to 2.43 J/cm^2 with increasing the ablated line widths and depths from 27.3 μm to 34.2 μm and from 1.53 μm to 2.14 μm, respectively. In addition, the ablated line widths and depths increased from 6.2 μm to 9.9 μm and from 2.2 μm to 3.5 μm when decreasing the scanning speeds of galvanometers from 2000 mm/s to 200 mm/s, respectively. When the UV laser fluence set 3.027 J/cm^2 for the direct writing the multi-graphene films, the ablated trench was electric isolation after measuring the I-V curve. The output current values were zero at different input voltages that could prove the electric isolation on both sides of ablated trenches.