氮化銦基薄膜磁性與超導特性之研究

Magnetic and Superconductive properties of InN-based thin films

洪士育(Shih-Yu Hung)

指導教授 ： 張本秀

國立臺北科技大學/工程學院/資源工程研究所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00204

摘要

本論文探討氮化銦基薄膜之磁性與超導特性。氮化銦基薄膜為c軸取向之烏采結構，包括由分子束磊晶法製作之氮化銦薄膜、以有機金屬化學沉積法製作之氮化銦鎂薄膜、以及由離子佈植方式製備之氮化銦錳薄膜；同時藉由快速熱處理製程使氮化銦錳薄膜品質最佳化。
利用X-ray繞射儀、掃描式電子顯微鏡分析結構與表面特性；電性則藉由霍爾量測分析之；磁性與超導方面則以超導量子干涉儀量測磁化強度隨溫度變化之關係，分別以零場冷卻以及場冷卻模式探討之。
研究結果顯示：
1. 氮化銦具有順磁性，可以居里順磁公式擬合，發現樣品中之磁矩間有微弱之交換交互作用。樣品在1.8 K未出現超導相變，認為與其順磁性磁矩有關。
2. 氮化銦鎂薄膜，在5 K出現超導相變, 推測鎂離子摻雜，能有效屏蔽氮化銦之順磁性磁矩，有利電子配對成庫柏對使樣品超導。
3. 氮化銦錳薄膜，錳離子摻雜使氮化銦薄膜有較大順磁性磁矩；樣品在3 K出現超導相變，藉由快速熱處理製程使氮化銦錳薄膜品質最佳化後，超導相變溫度提高到3.8 K。推測與其順磁性磁矩被有效屏蔽有關。其超導為第二類超導體，具各向異性。

關鍵字

氮化銦基薄膜 ； 磁性 ； 超導 ； 快速熱退火 ； 分子束磊晶 ； 有機金屬化學沉積

並列摘要

The purpose of this study is to investigate the magnetic and superconductive properties of InN-based thin films. InN-based thin films studies here are c-axis orientated Wurtzite structure with GaN buffer layer and sapphire substrate. The InN is fabricated by MBE, the Mg-doped InN is fabricated by MOCVD and Mn-Doped InN is by Mn ion implantation method. RTP is used to optimize the quality of the films.
The structures and surface properties were studied by XRD, SEM and EDX. Transport properties were made by Hall measurements with van de pauw geometry. Temperature-dependent magnetization is studied by SQUIDs with zero-filed cooling and field cooling modes.
Our results are summarized as following:
1. The temperature-dependent magnetization curve of InN thin films was fitted by Curie-Weise law and Langevin diamagnetic part. The results show that there is paramagnetic contribution of InN. Due to the magnetic moment, InN did not show superconductivity at T =1.8 K.
2. Mg-doped InN show superconductivity at 5 K for the effect of Mg doping can screen the magnetic moment in InN.
3. The paramagnetic component of Mn-doped InN is larger than that of InN and sample show superconductivity at 3.8 K. This scenario suggests that the magnetic moment of Mn-dopen InN is screened and the electrons can become cooper pairs thus show superconducting Meissner effect. Mn-doped InN is type II superconductor and show anisotropic magnetic properties.

並列關鍵字

InN ； MOCVD ； MBE ； RTA ； Superconductivity ； Curie Law

參考文獻

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