氧化鋅鋁/P型氮化鎵異質結構之光、電特性研究

Study of optoelectronic of ZnO:Al/p-type GaN heterostructure

張原清(Yuan-ChingChang 張原清)

指導教授 ： 柯文政

元智大學/工程學院/先進能源碩士學位學程/碩士(2012年)

摘要

本論文研究在p型氮化鎵薄膜上製備具歐姆特性之 氧化鋅鋁透明導電層。有別於一般須在p型氮化鎵薄膜上先沈積金屬Ni或NiO，才能製備具歐姆特性之透明導電層，本論文提出使用較低壓力下成長之p型氮化鎵薄膜，可以直接在其上成長具有近似歐姆接點特性之氧化鋅鋁透明導電層。進一步利用退火製程在溫度700℃時發現可以改善歐姆接點特性。實驗中分別在氧化鋅鋁薄膜上蒸鍍金屬鋁，在p型氮化鎵薄膜上蒸鍍鎳/金電極，透過電流-電壓特性量測氧化鋅鋁/p型氮化鎵結構電傳導特性，經由理論模型分析，以普爾－法蘭克發射（Poole-Frenkel emission）傳導機制為主。另一方面，我們分別以電容-電壓量測方法分析高壓及低壓成長之p型氮化鎵薄膜與金屬Ni形成之蕭特基能障，分別為0.918 eV及0.845 V。而使用X射線光電子能譜儀觀察3d核層之譜峰位置，訂出p型氮化鎵表面費米能階，相較於高壓成長之p型氮化鎵薄膜，低壓成長之p型氮化鎵薄膜表面費米能階位置相當靠近傳導帶，降低氧化鋅鋁與p型氮化鎵薄膜之能障，使歐姆接點特性得以獲得改善。

關鍵字

P型氮化鎵 ； 氧化鋅鋁

並列摘要

This study presents a method to achieve a transparent conducting Al-doped ZnO (AZO) ohmic-like contact behavior to p-GaN films. Without using the Ni or NiO interlayer, AZO ohmic-like contact layer was grown directly on the low-pressure growth of p-GaN films. In addition, the ohmic-like behavior of AZO contact layer can be improved by using annealing process at 700 ℃. The electrical property of AZO/p-GaN heterostructure was analyzed by current-voltage (I-V) curve. The Poole-Frenkel emission conduction mechanism dominated the I-V behavior of AZO/p-GaN heterostructure. The Schottky barrier height which measure by the capacitance-voltage method for the metal Ni on high-pressure growth and low-pressure growth of p-GaN films were 0.918 eV and 0.845 eV, respectively. Compared to high-pressure growth p-GaN films, the surface Fermi level determined by the Ga 3d core-level peak on low-press growth p-GaN films lies closer to the conduction band edge. The reduction in barrier height due to the high nitrogen vacancy (VN) density pinned the surface Fermi level close to the conduction band edge, and allowed the electrons to easily flow over the barrier from the metal into the p-GaN films. Thus, a AZO ohmic-like contact can be achieved on the low-pressure growth p-GaN films by the surface inversion method.

並列關鍵字

p-GaN ； AZO

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