以有機金屬化學氣相磊晶成長之摻鎂氮化鎵薄膜其特性研究

Characterizations of Mg-doped GaN Thin Films Grown by MetalOrganic Chemical Vapor Deposition System

林逸峻(Yi-Chun Lin)

指導教授 ： 廖森茂

中原大學/工學院/電子工程研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100133

摘要

中文摘要
氮化鎵及其相關材料為目前發展藍綠光元件的關鍵材料。本論文實驗係利用常壓有機金屬化學氣相磊晶的方法來製備調變鎂摻雜之Cp2Mg氣體流量和變化成長溫度的摻鎂氮化鎵薄膜。利用光激螢光(PL)，霍爾量測(Hall measurement)及X光繞射(XRD)等方法量測並分析其光性、電性、物性。
實驗結果，顯示光激螢光發光波長和載子濃度隨著鎂摻雜之氣體流量比改變。從n-type 轉變到 p-type 導電性的[Mg]/[Ga]臨界流量比約為1.9%。若鎂摻雜之氣體流量低於此臨界流量則氮化鎵薄膜呈現n-type 的導電性。相反地，當流量比超過這個臨界流量後，摻鎂的氮化鎵薄膜開始從n-type 轉變到 p-type 導電性，且與流量比有密切的關聯。
光激螢光光譜顯示隨著鎂摻雜氣體流量的增加分別出現兩個主導的波峰。在低流量時為導電帶到鎂所形成受子能階之能量躍遷(eA)，發光波長在382 nm。隨著鎂摻雜量增加，最後會出現一個較寬的藍色波峰，發光波長在430nm。我們認為這可能是鎂相關錯合物所造成的深能階施子躍遷至受子能階(DAP)的發光光譜。
隨著磊晶溫度增加，氮化鎵薄膜的成長速率逐漸變慢且鎂摻雜的效率也隨溫度升高而提升。當鎂的摻雜效率過高時會形成缺陷使薄膜品質降低。整體言之，本論文針對摻鎂氮化鎵薄膜做光性、電性及物性的研究，可提昇其薄膜磊晶品質，這將有助於氮化鎵系列元件特性之改善。

關鍵字

氮化鎵 ； 鎂 ； 有機金屬化學氣相磊晶

並列摘要

Abstract
Until now, GaN and its related materials are the key issue for developing the blue-green devices. In this thesis , the investigation magnesium doped GaN films with various Cp2Mg flow rate and growth temperature was conducted in atmospheric pressure metalorganic chemical vapor deposition(AP-MOCVD). The optical, electrical and physical characteristics were analyzed and measured using room temperature photolumiscence(PL), Hall-measurement and XRD, respectively.
Experimental data indicate that the photoluminescence peak wavelength and carrier concentration varies in different Cp2Mg flow rate.
The crossover from n-type to p-type conduction occurs approximately at 1.9% of [Mg]/[Ga] mole flow ratio . Below the critical value , the Mg-doped GaN thin films show n-type conductivity. In opposites , above the specified ratio of 1.9% reveals p-type conduction, which is intimately related to the Cp2Mg molar fraction.
Photoluminescence data reveals that two dominant peaks appear with increasing Cp2Mg flow rate. At low Cp2Mg flow rate shows a conduction band to acceptor (eA) transition peaked at 382nm. While the more magnesium is doped, a broader blue feature of 430nm wavelength is eventually observed. It is suggested, that associated with a DAP transition involving with deep donors introduced by the high concentration of magnesium solid incorporation.
The GaN growth rate becomes slow with increasing growth temperature, although Mg doping efficient is independent of the growth temperature. The highly added magnesium dopants are introduced into GaN film, leading to relative vacancies and crystalline defects, that consequently degrade the thin film quality and decrease hole concentration .
As a whole, the incorporation of optical, electrical and physical properties will help us to improve the crystalline characterizations of GaN thin films and to enhance the performance of the relevant nitride-based devices.

並列關鍵字

GaN ； MOCVD ； Mg

參考文獻

[10] B. R. Pamplin, “Crystal Growth” second edition, (1979)

[12] S. Z. Sze, “Physics of Semiconductor Devices” second edition,(1985)

[13] A. K. Fung, J. E. Borton, M. I. Nathan, J. M. Vanhove, R. Hickman II, P. P. Chow, and A. M. Wowchak, J. Electron. Mater. 28, 5(1999)

[16] G.B.Ren,D.J.Dewsnip,D.E.Lackison,J.W.Orton,T.S.Cheng C.T.Foxon,Materials Science and Engineering B43 p.242-245(1997)

[18] H.B.Bebb and E.W. Williams, Semicond. Semimet.,8(1972)4-5