氮化鎵相關材料及元件製程技術之研究

Abstract

本論文內容主要為乾式蝕刻應用於GaN材料及發光元件製程之研究,首先先探討使用感應耦合式電漿蝕刻( ICP )系統於固定蝕刻氣體流量Cl2/Ar=10/25sccm(比例2:5)時,蝕刻undoped GaN與p-GaN試片,而變化其他蝕刻參數如:腔體壓力、RF偏壓功率及ICP功率等,進而分析蝕刻速率、蝕刻表面的粗糙度與側壁蝕刻垂直度,運用此實驗數據於GaN發光元件的製作,並展示其光性與電性結果。此外在EEL(Edge Emitting Laser) GaN製作上,利用蝕刻參數為:Cl2/Ar=50/20sccm(比例5:2),ICP功率=300W,RF偏壓功率=30W及腔體壓力為5mTorr,得到蝕刻側壁非常平順(smooth)的雷射鏡面與蝕刻後表面粗糙度為1.29nm的實驗結果。而在GaN nano structure研究中,固定相關蝕刻參數:Cl2/Ar=10/25sccm(比例2:5),ICP功率=200W,RF偏壓功率=200W,當腔體壓力從2.5mTorr增加至30mTorr時,得到GaN nano structure 之密度隨著腔體壓力增加而增加的結果,而在腔體壓力增加至30mTorr時,可得到密度大約為3*1010cm-2尺寸大小大約為20nm~50nm之GaN nano structure array, ,進而可利用ICP蝕刻來製作與控制GaN nano structure之光電元件。

In this thesis,we investigate the processing of GaN materials and photonic devices using dry etching.First,we analysis the etching rates,etched surface roughness and etching sidewall of undoped and p-GaN with fixed etching gas of Cl2/Ar for various chamber pressure,RF bias power and ICP power.Using the result of etching process , we fabricated the GaN photonic device and showed the optical and electrical properties. For etching of EEL laser structure,using high Cl2 ratio (Cl2 / Ar = 50 / 20 sccm), ICP power=300W, RF bias power=30W and low chamber pressure 5 mTorr, a smooth mirror-like facet and the etched surface roughness of about 1.3nm was obtained by ICP system. Using these etching parameters, mirrorlike facets can be obtained which can be used for the fabrication of nitride-based laser diodes. For the investigation of the GaN nano structure,we report a novel method to fabricate controllable dimension and density of GaN structure using ICP etching.The etching condition was Cl2/Ar flow rate of 10/25 sccm and ICP/Bias power of 200/200W and the GaN nanorods and array were fabricated with density of 108 ~ 1010 cm-2 and dimension of 20~100nm by varying the chamber pressure from 10 mTorr to 30 mTorr. The technique offers an one-step, controllable method of fabrication of GaN nano-structures and should be applicable for fabrication of GaN based nano-optoelectronic devices.