選擇性雷射燒結對鋁摻雜氧化鋅奈米顆粒微結構與熱電性質之影響

Abstract

鋁摻雜氧化鋅（Aluminum-doped Zinc Oxide, AZO）奈米顆粒薄膜具備良好導電性與穩定性，為熱電元件之潛力材料。本研究利用選擇性雷射燒結（Selective Laser Sintering, SLS）技術，調控雷射能量密度與掃描速度，系統性探討不同摻雜濃度（0.5、1、2 wt%）AZO 薄膜之微觀形貌、導電性與熱電性質的關聯性。 透過微觀型態分析，提出了不同形貌影響載子濃度、遷移率之機制，並且搭配霍爾量測儀結果顯示，載子濃度為導電率的主要控制因子，遷移率則隨摻雜濃度上升而下降。隨著雷射強度上升，席貝克係數絕對值呈現先上升後下降之趨勢，反映薄膜在進入燒蝕階段後限制熱電性能表現，而最佳席貝克係數於溫差為40 K時為108.33 μV/K。 進一步計算功率因數（Power Factor）發現，其最佳表現皆對應於薄膜燒結最為緻密之條件，最佳PF於溫差為40 K時為5.79 μW/mK^2。穩定性評估方面，初步結果指出 AZO 薄膜在空氣中具備良好之熱電性穩定性，顯示其應用潛力。 總體而言，透過本研究所使用之選擇性雷射燒結，可有效調控 AZO 薄膜之微觀結構、載子濃度與熱電性質，並成功於基板上製備具差異化熱電表現的導電薄膜。此結果證明雷射燒結技術在熱電薄膜製程中具有高度潛力，未來可應用於微型熱電元件或感測材料之製備上。

Aluminum-doped zinc oxide (AZO) nanoparticle thin films exhibit excellent electrical conductivity and stability, making them promising candidates for thermoelectric devices. In this study, selective laser sintering (SLS) was employed to regulate laser energy density and scanning speed, enabling a systematic investigation of the correlations among microstructure, electrical conductivity, and thermoelectric properties of AZO films with different doping concentrations (0.5, 1, and 2 wt%). Through microstructural analysis, mechanisms describing how morphology influences carrier concentration and mobility were proposed. Combined with Hall measurement results, it was found that carrier concentration is the dominant factor governing electrical conductivity, while mobility decreases with increasing doping concentration due to impurity scattering. As laser intensity increases, the absolute value of the Seebeck coefficient initially rises and then declines, indicating performance degradation in the ablation stage. The highest measured Seebeck coefficient was −108.33 μV/K at a temperature difference of 40 K. Further calculation of the power factor (PF) showed that the optimal performance was consistently associated with the most densely sintered films. The highest PF achieved was 5.79 μW/mK² at a temperature difference of 40 K. Preliminary stability evaluations showed that AZO films retained good thermoelectric performance under ambient air exposure, demonstrating their potential for practical application. Overall, the selective laser sintering method effectively modulates the microstructure, carrier concentration, and thermoelectric properties of AZO films, enabling the fabrication of conductive films with distinct thermoelectric characteristics directly on substrates. These results confirm the high potential of laser sintering in thermoelectric thin-film fabrication, with future applicability in microscale thermoelectric devices and sensing materials.