隨著柔性電子與永續電子元件的發展，天然高分子材料因具備可降解性、生物相容性與低環境負擔，逐漸受到電阻式隨機存取記憶體（resistive random-access memory, RRAM）領域關注。然而，天然高分子薄膜常面臨成膜不均、導電通道不穩定與 ON/OFF ratio 不足等問題，限制其電性穩定度與實際應用。相較於其他天然高分子材料，羅望子種子具有較高的多醣含量，其種仁中羅望子多醣體含量約可達 39–50 %，且來源容易取得、成本低，具備作為綠色電子材料之潛力。因此，本研究以羅望子多醣體（Tamarind Seed Polysaccharide, TSP）作為主動層，製備 Al/TSP/ITO 結構 RRAM 元件，並探討電漿清潔、溶劑選擇與 TSP 濃度對元件電性之影響。
結果顯示，電漿清潔可改善 ITO 表面親水性與界面接觸品質，根據相關文獻中氧電漿處理降低 ITO 表面接觸角之結果，可推測其有助於提升 TSP 溶液鋪展性與薄膜/電極界面接觸，進而改善元件切換穩定性與 ON/OFF ratio；而 PBS 溶劑可提供穩定離子環境，並使薄膜呈現較明顯的表面形貌變化與 RMS roughness 差異，有助於導電通道形成與侷限。在最佳化條件比較中，1.0 wt% TSP/PBS 元件展現最佳雙極性電阻切換特性，元件良率可達 60 %，ON/OFF ratio 可達 10³ 以上，並可穩定切換超過 100 次；在 0.1 V 讀取電壓下，元件於室溫與 80 °C 下皆可維持明顯可辨識之 ON/OFF ratio 超過 10⁴ 秒，顯示良好的資料保持能力與熱穩定性。
進一步應用於柔性基板時，元件於未彎折狀態下 ON/OFF ratio 約為 5 × 10²，即使彎折直徑降低至 1.5 cm 仍可維持約 1.1 × 10² 之開關比，顯示良好的可撓式操作穩定性與機械彎曲穩定性。整體而言，本研究證實透過電漿前處理、PBS 溶劑與 TSP 濃度最佳化，可改善薄膜鋪展性、界面接觸品質與離子輔助導電通道形成，進而有效提升 TSP 基 RRAM 之電性、熱穩定性與機械穩定性，未來可望延伸應用於穿戴式電子、生醫感測、暫態電子、物聯網感測節點及低功耗綠色記憶體系統。

With the development of flexible electronics and sustainable electronic devices, natural polymer materials have attracted increasing attention in the field of resistive random-access memory (RRAM) due to their biodegradability, biocompatibility, and low environmental impact. However, natural polymer thin films often suffer from poor film uniformity, unstable conductive pathways, and insufficient ON/OFF ratio, which limit their electrical stability and practical applications. Compared with other natural polymer materials, tamarind seeds contain a relatively high polysaccharide content, with tamarind seed polysaccharide accounting for approximately 39–50 % of the seed kernel. In addition, tamarind seeds are easily obtainable, low-cost, and have great potential as green electronic materials. Therefore, in this study, tamarind seed polysaccharide (TSP) was employed as the active layer to fabricate Al/TSP/ITO-structured RRAM devices. The effects of plasma cleaning, solvent selection, and TSP concentration on the electrical characteristics of the devices were systematically investigated.
The results show that plasma cleaning can improve the surface hydrophilicity of ITO and enhance the interfacial contact quality. Based on previous reports showing that oxygen plasma treatment can significantly reduce the contact angle of ITO, it can be inferred that plasma treatment facilitates the spreading of the TSP solution and improves the film/electrode interfacial contact, thereby enhancing the switching stability and ON/OFF ratio of the device. Meanwhile, PBS solvent provides a stable ionic environment and induces more pronounced changes in film morphology and RMS roughness, which are beneficial for the formation and confinement of conductive pathways. Among the optimized conditions, the 1.0 wt% TSP/PBS device exhibited the best bipolar resistive switching characteristics, with a device yield of 60 %, an ON/OFF ratio exceeding 10³, and stable switching endurance for over 100 cycles. Under a read voltage of 0.1 V, the device maintained clearly distinguishable ON and OFF states for more than 10⁴ s at both room temperature and 80 °C, demonstrating good data retention and thermal stability.
Furthermore, when applied to a flexible substrate, the device exhibited an ON/OFF ratio of approximately 5 × 10² in the unbent state. Even when the bending diameter was reduced to 1.5 cm, the ON/OFF ratio remained approximately 1.1 × 10², indicating good flexible operation stability and mechanical bending stability. Overall, this study demonstrates that plasma pretreatment, PBS solvent, and optimization of TSP concentration can improve film spreading, interfacial contact quality, and ion-assisted conductive pathway formation, thereby effectively enhancing the electrical, thermal, and mechanical stability of TSP-based RRAM devices. These results suggest the potential application of TSP-based RRAM in wearable electronics, biomedical sensing, transient electronics, Internet of Things sensing nodes, and low-power green memory systems.

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