在本次研究中，我們製作了不同元件結構的氧化鎵電阻式記憶體，並探討結構的改變對電阻切換特性的影響。首先，我們在玻璃基板上沉積10奈米的鈦以及50奈米的鉑作為下電極，接著沉積50奈米的氧化鎵作為電阻轉換層，最後沉積50奈米的銅做為上電極，這是傳統的MIM結構，為了改善電阻式記憶體的切換特性，我們在電阻轉換層的製程上做出調整，首先，沉積25奈米的氧化鎵，再來沉積5奈米的銅插入層，最後再沉積25奈米的氧化鎵，並透過快速退火使插入層的銅形成奈米微粒均勻分布在電阻轉換層中，藉此讓電阻式記憶體的導電燈絲路徑更加穩定，測量結果顯示，摻雜銅的元件比傳統 MIM 結構元件具有更好的電阻切換特性，其開關比達到10^5，且展現了超過 2000 次切換循環的卓越耐受性。
再來，我們在電阻轉換層已經插入銅奈米微粒的情況下改變上電極的金屬，原先的銅做為上電極的電阻式記憶體屬於金屬離子的傳導機制，我們更換成鈦以及鎳金屬用來作為上電極，這兩種金屬為氧空缺的傳導機制，用來驗證插入銅奈米微粒的製程優化是否對不同的傳導機制都能做出改善，結果顯示插入銅奈米微粒只能對金屬離子傳導機制的電阻式記憶體有明顯的特性改善。
接著，我們將電阻轉換層中插入的金屬由銅替換成銀，銅和銀為金屬離子的傳導機制中最具代表性的兩種金屬，藉此來探討銀插入層形成奈米微粒後能否達成和銅插入層一樣的效果，結果顯示插入銀並無法做出明顯的改善。
最後，除了傳統的電壓電流量測外，我們還進行了直流脈衝量測，結果顯示脈衝量測只能承受大約100次的切換循環，和傳統量測方式的超過2000次的切換循環有顯著差距，未來還有再改善的空間。

In this study, we fabricated gallium oxide (Ga2O3) -based resistive random-access memory (RRAM) with various device structures and investigated the impact of structural modifications on their resistive switching characteristics. Initially, a conventional metal-insulator-metal (MIM) structure was prepared by depositing 10nm of Titanium (Ti) and 50 nm of Platinum (Pt) as the bottom electrode on a glass substrate, followed by a 50 nm gallium oxide active layer and a 50 nm Copper (Cu) top electrode. To improve the switching performance, we modified the fabrication process of the active layer. This involved depositing a 25 nm gallium oxide layer, followed by a 5 nm Copper insertion layer, and a final 25 nm gallium oxide layer. Subsequently, Rapid Thermal Annealing (RTA) was employed to transform the Cu insertion layer into uniformly distributed nanoparticles within the active layer. This architectural refinement serves to stabilize the formation and rupture paths of the conductive filaments. Measurement results demonstrate that the Cu-doped devices exhibit superior resistive switching characteristics compared to the traditional MIM structure. The optimized devices achieved a high on/off ratio of 10^5 and displayed excellent reliability with an endurance exceeding 2,000 switching cycles.
Furthermore, while maintaining the Cu nanoparticle-embedded switching layer, the top electrode (TE) material was varied to investigate the impact of different conduction mechanisms. The original device with a Cu TE operates via a metallic ion conduction mechanism (ECM). To verify whether the Cu-nanoparticle optimization process universally improves different switching mechanisms, Ti and Ni were employed as top electrodes, as these metals typically involve an oxygen vacancy-driven conduction mechanism (VCM). The experimental results revealed that the insertion of Cu nanoparticles significantly enhances the resistive switching characteristics only for devices based on the metallic ion conduction mechanism, while showing limited impact on those governed by oxygen vacancies.
Subsequently, the metal insertion layer within the resistive switching layer was transitioned from copper (Cu) to silver (Ag). As Cu and Ag are the two most representative metals in electrochemical metallization (ECM) conduction mechanisms, this modification aimed to investigate whether an Ag insertion layer, upon forming nanoparticles, could achieve a similar enhancement effect as observed with Cu. Interestingly, the experimental results indicated that the insertion of Ag did not lead to any significant improvement in the resistive switching characteristics.
Finally, in addition to conventional direct current (DC) measurements, pulsed voltage-current (I-V) measurements were conducted to further evaluate the device's reliability. The results indicated that the device could only withstand approximately 100 switching cycles under pulsed conditions. This represents a significant discrepancy compared to the endurance of over 2,000 cycles observed in conventional DC measurements. These findings suggest that while the Cu-nanoparticle insertion effectively stabilizes DC switching, there remains substantial room for improvement in the device's stability under high-speed pulse operations in future research.

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