本實驗利用氣相傳輸法在氧氣環境下以金屬鋅顆粒為蒸發源，製備出鋅-氧化鋅核殼結構奈米線。此核殼結構其內層鋅直徑約為53 nm，外層包覆一層厚度約7.5 nm的氧化鋅，並沿[112 ‾0]方向成長。經過熱氧化之後，鋅-氧化鋅奈米線內部的金屬鋅向外擴散成長，造成奈米線內部空洞，形成多晶之氧化鋅奈米管。以此鋅-氧化鋅核殼結構以銀及銦為電極製成金屬-半導體-金屬光電偵測元件。研究結果顯示以銦電極製成之光偵測器其最大光響應在300 nm為1.6 A/W，光電流下降時間為τ1=50 s、τ2=595 s，而以銀為電極之光偵測器其最大光響應在300 nm為12 A/W，光電流下降時間為τ1=19 s、τ2=202 s。相較於銦電極之光偵測器，以銀為電極之光偵測器具有較高之光響應及較快之光電流下降時間，歸納原因是由於銀與氧化鋅形成蕭特基接面，而銦與氧化鋅形成歐姆接面。當蕭特基接面的金屬-半導體-金屬照光時，逆向偏壓的蕭特基接面空乏區因吸收光子而產生一反向之光電壓，此光電壓使蕭特基位障下降進而使逆偏電流急遽上升而產生較高之光響應。

Single-crystalline Zn-ZnO core-shell nanofibers have been prepared by thermal evaporation of metallic Zn in an oxygen atmosphere. The diameter of the Zn core is ~53±1.0 nm while the thickness of the outer ZnO shell is 10±1.5 nm, both are single crystalline and grow along the[112 ‾0]direction. Post-growth annealing leads to out-diffusion and oxidation of the Zn core that result in the formation of polycrystalline ZnO nanotubes. Metal-semiconductor-metal photodiodes (PDs) are fabricated by depositing In and Ag interdigitated electrodes on Zn-ZnO core-shell nanofibers. PDs fabricated utilizing In contacts exhibit a maximum responsivity of 1.6 A/W at 300 nm with a decay time of τ1=50 s andτ2=595 s. In contrast, photodiodes fabricated utilizing Ag contacts exhibit a maximum responsivity of 12 A/W at 300 nm with a decay time of τ1=19s andτ2=202 s. The improved responsivity and decay time is attributed to the formation of Schottky barrier between Ag and ZnO.

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