不同表面處理對於氧化鋅蕭特基二極體電特性影響之研究

Electrical Characteristics of ZnO Schottky Diodes for Different Surface Treatment

姚筱茹(Shiau-Lu Yao)

指導教授 ： 劉代山

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2011年)

摘要

本研究於室溫下利用射頻磁控式共濺鍍系統，選擇氧化鋅作為濺鍍靶材，在矽基板上沉積本質氧化鋅薄膜，並利用氧氣熱處理製程製作具有電子濃度為1014~ 1015 cm−3之n型氧化鋅薄膜，選擇氧化鋅與氧化銦錫作為共濺鍍靶材，在氧化鋅上沉積n型氧化鋅-氧化銦錫共濺鍍薄膜（Zn/(Zn+In) = 90 at.%），並利用氧氣熱處理製程促使晶體成長後，蒸鍍鈦/鋁金屬為歐姆電極以及與未摻雜氧化鋅薄膜表面處理後沉積鎳/金作為蕭特基二極體之接觸電極，並使用半導體參數分析儀進行電性量測，研究結果顯示，未表面處蕭特基位障為0.59 eV、雙氧水表面處理後蕭特基位障為0.87 eV、硫化銨表面處理後蕭特基位障0.84 eV，發現表面處理後其蕭特基位障大幅提升。本研究藉由X光光電子能譜儀、光激發螢光光譜儀量測探討表面處理前後缺陷變化及機制。結果顯示經由雙氧水未摻雜氧化鋅薄膜表面O-H化學鍵結增加，造成空乏區變寬且能帶向上彎曲；經由硫化處理後薄膜表面之硫原子補償氧缺陷產生Z-S化學鍵結，因此，分別藉由雙氧水、硫化表面處後，可促使補償效應降低表面濃度以及鈍化氧化鋅表面態位密度。
接著分別利用氧化銦錫-氧化鋅共濺鍍透明導電薄膜（Zn/(Zn+In)=33 at.%）作為歐姆接觸電極並與未摻雜氧化鋅薄膜表面處理後沉積鎳/金作為蕭特基二極體之接觸電極以及利用氧化銦錫-氧化鋅共濺鍍透明導電薄膜為歐姆接觸電極並以稀釋鹽酸蝕刻後之未摻雜氧化鋅薄膜表面處理沉積鎳/金為蕭特基二極體之接觸電極，藉由半導體參數分析儀進行電性量測，研究顯示利用透明導電薄膜為歐姆接觸電極並使用雙氧水以及硫化銨進行表面處理製作蕭特基二極體，可大幅提升蕭特基二極體的整流特性。

關鍵字

氧化鋅 ； 蕭特基二極體 ； 表面處理

並列摘要

In this study, the intrinsic ZnO films were grown on silicon substrate by rf magnetron co-sputtering system, using target of ZnO (purity 99.99%). The ZnO films were annealed under oxygen ambient and processed an electron carrier concentration of 1015 ~ 1016 cm−3, and deposited cosputter film on the undoped ZnO at an atomic ratio of 90% [Zn / (Zn + In) at.%] was annealed under oxygen ambient and possessed an electron carrier concentration of 1017 ~ 1018 cm−3. A standard photolithography technique was used to pattern of Schottky diode, and with various surface passivation on the films, respectively. Ti/Al and Ni/Au metal were deposited on the cosputered films by electron beam evaporation. The analyzer measured by Current-Voltage. The results shown that Schottky barrier height markedly increased from 0.59 eV for unpassivated Schottky diode to 0.87 eV and 0.84 eV for the Schottky diode, with hydrogen peroxide and (NH4)2SX passivation on the undoped ZnO layer surface.This study the surface treatment defects before and after and mechanisms measurement by Photoluminescence (PL), X-ray photoelectron spectroscopy (XPS). It is shown that ZnO films surface increased O-H accept like defect by hydrogen peroxide treatment, leading to the wider depletion region and exhibits upward band bending toward the surface. It is found that the sulfur atoms occupation of oxygen defect and the formation of Zn-S bonds by (NH4)2Sx treatment, hence the surface treatment is fairly effective in reducing surface state density. Then, the ZnO Schottky diode was fabricated with co-sputtering transparent electrode as ohmic contacts electrode, the Ni/Au metallization as Schottky contacts electrode and co-sputtering transparent electrode 33% [Zn / (Zn + In) at.%] as ohmic contacts electrode, the Ni/Au metallization as Schottky contacts electrode on the etching ZnO surface, respectively. The results showed that effective in reduced surface state density and exhibited rectifying behavior after surface treatment.

並列關鍵字

Zinc Oxide ； Schottky diode ； Surface treatment

參考文獻

參考文獻

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