具有高介電閘極氧化層之增強型氮化鋁鎵/氮化鎵金屬：氧化物-半導體異質場效電晶體研製與分析

Abstract

本報告旨在應用臭氧水氧化製程技術(ozone water oxidization treatment)研製一具有增強型操作之氮化鋁鎵/氮化鎵金屬-氧化層-半導體異質結構場效電晶體。藉由薄化蕭特基接觸層(Schottky contact layer)使元件獲致增強型(Enhancement mode)元件操作，進而應用臭氧水氧化製程技術，在元件之氮化鋁鎵蕭特基接觸層表面形成一具有奈米尺寸、高介電常數之氧化鋁(Al2O3)薄膜，同時作為閘極介電層與表面鈍化層，以有效降低表面缺陷以及閘極漏電流，大幅改善元件工作特性。 本報告藉量測脈衝電流電壓（I-V），低頻雜訊和比較Hooge係數來驗證通過氧化物鈍化效應來改善表面品質的效果。與使用相同磊晶製程的傳統具有蕭特基閘極結構異質場效電晶體相較之下，元件的電流增益，電流驅動密度，崩潰電壓，電流開/關比都更加優異。

The purpose of this work is to investigate Al0.25Ga0.75N/GaN enhancement-mode (E-mode) metal–oxide–semiconductor hetero -field- electrical transistors (MOS-HFETs) obtained by the ozone water oxidization method. Thin Schottky contact barrier layer is devised to achieve enhancement-mode device operation and then applying a process of ozone water oxidation to form an AlGaN layer on the surface of the AlGaN schottky contact layer (Al2O3) thin film with nano-size and high dielectric constant as gate dielectric layer and surface passivation layer to effectively reduce surface defects and gate leakage current and greatly improve the operating characteristics of the device. Pulse current–voltage (I–V), low-frequency noise, and Hooge coefficient measurements are compared to verify the interface quality improved by the oxide passivation effect. In comparison, a conventional Schottky-gate HEMT device is also fabricated on the same epitaxial sample. Enhanced device gain, current drive density, breakdown, on/off current ratio are better than conventional HFETs in this work.