MOCVD製程壓力對ε-Ga2O3薄膜結構與光電特性之影響與深紫外光感測器應用

Dependence of Process Pressure on Characteristics of MOCVDε-Ga2O3 Films for Deep Ultraviolet Photodetector Applications

本研究利用有機金屬化學氣相沉積法於藍寶石基板上沉積ε-Ga2O3薄膜，透過系統性調控製程壓力探討壓力變化對薄膜結晶品質、晶相穩定性與深紫外光感測特性之影響。結果指出當製程壓力為15 torr時呈現最佳結晶品質，半高寬為196.7 arcsec，晶粒尺寸達537.1 nm，此條件製備之感測器光暗電流比達1，268。進一步導入原子層沉積法沉積氧化鋁鈍化層，抑制薄膜表面缺陷並改善載子傳輸，使光暗電流比達14，220，較未鈍化之元件提升約1，025%，整體性能大幅改善。綜上所述經製程壓力最佳化與表面鈍化製程後ε- Ga2O3深紫外光感測器展現優異結晶品質、低暗電流與高光暗電流比，在深紫外光偵測領域具高度應用潛力。未來可應用於深紫外感測、國防航太與智慧感測整合系統，具備實質商品化與產業發展潛力。

In this study,ε-Ga2O3 thin films were deposited on sapphire substrates by metal organic chemical vapor deposition, the influence of process pressure on crystallographic quality, phase stability, and deep-ultraviolet photodetector performance was systematically investigated. The results demonstrate that a process pressure of 15 torr yields the optimal film quality, characterized by a minimum x-ray-diffraction full width at half maximum of 196.7 arcsec and an enlarged grain size of 537.1 nm, indicating enhanced crystalline ordering and reduced structural disorder. Photodetectors fabricated under this optimized condition exhibit a photo-to-dark current ratio of 1268, confirming the beneficial role of pressure-controlled growth in suppressing leakage current pathways. Furthermore, the introduction of an Al2O3 surface passivation layer deposited by atomic layer deposition effectively mitigates surface defect states and improves carrier transport behavior, leading to a pronounced reduction in dark current. As a result, the photo-to-dark current ratio is significantly enhanced to 14,220, corresponding to an improvement of approximately 1,025% compared with devices without passivation, highlighting the critical contribution of interface engineering to device performance. Overall, the combined optimization of growth pressure and surface passivation enablesε-Ga2O3 deep-ultraviolet photodetectors to achieve superior crystalline quality, low dark current, and high photo-to-dark current ratio. These results underscore the strong potential ofε-Ga2O3-based devices for deep-ultraviolet sensing applications and indicate promising prospects for practical implementation in ultraviolet sensing modules, defense and aerospace ultraviolet detection, and intelligent sensing platforms integrated with advanced semiconductor technologies.