本實驗使用分子束磊晶系統，在Al2O3(11‐20)上成長氧化鋅摻雜鈷多層膜([ZnO20Å/Co1Å]25)，再利用不同的退火條件，製備出低載子濃度的樣品，由RHEED 與XRD 實驗結果得知，退火前後樣品仍為高品質的單晶結構。此外，利用各種磁電性量測工具的分析(SQUID、XAS、Hall effect)，對低載子濃度（insulating regime）的氧化鋅摻雜鈷的單晶薄膜樣品的磁性機制來源做出了一個新的解釋。最新第一原理理論計算推測在氧化鋅摻雜鈷的系統，Co離子能帶分裂形成一個自旋向上和自旋向下的能帶，自旋向上的能帶會位於價帶，並且和淺層受體能階（shallow donor level）的自旋向上的電子產生s-d交互作用(s-d exchange)將其束縛住，而Co自旋向下的能帶則會再分裂成2個能帶，其中一個為空的能階位於導帶的下緣，縮短了和缺陷所形成的淺層受體能帶（shallow donor level）之間的能隙。由於淺層受體能帶的自旋向上的電子被束縛住，所以只有淺層受體能帶的自旋向下的電子可以躍遷到導帶(conduction band)，所以造成淺層受體能帶自旋淨磁矩產生磁性訊號。同時我們的鐵磁訊號的強弱會隨著溫度上升而上升的原因，也從這個新的磁性機制模型找到了解釋。

In this study, we prepared [ZnO20Å/Co1Å]25 on Al2O3(11‐20) substrates by Molecular Beam Epitaxy(MBE).The samples were annealed with different conditions by a rapid thermal annealing(RTA) to control the carrier concentration.The investigation by RHEED and XRD concluded that High quality single crystal films were grown before and after annealing a.Furthermore,from the results of SQUID,XAS and Hall effect,we study a new model about the origins of ferromagnetism in Co-doped ZnO at insulating regime.For Co:Zn DMS,a recent theoretical work by Dr.J.Chen indicated that the energy states of Co can be split as the states of spin-up and spin-down.Interestingly,the Co spin-up state is located at valence band,and has s-d exchange with the spin-up electrons in the shallow donor level (induced by defects).The spin-down state of Co can be further spilt into two states,one of which is an empty state at the bottom of conduction band. Due to the spin-up electrons of shallow donor level are bound by the s-d exchange interaction. So that,only the spin-down electrons of shallow donor level can be easily excited to the conduction band. We concluded that the origin of magnetization in Co:ZnO can be attributed to the net spin moment in shallow donor level.The new proposed model can also explain the anomalous M(T) behavior that magnetization can be enhanced with increasing of the temperature.

第一章
[1.1] 黃榮俊、許華書，物理雙月刊，26 期4 卷2004 年8 月，p.599
[1.2] 胡裕民，物理雙月刊，26 期4 卷2004 年8 月，p.587
[1.3] H. Ohno et al., Science, 281 (1998), 951
[1.4] T. Deitl, H. Ohno et al., Science, 287 (2000), 1019
[1.5] A.J. Behan, A. Mokhtari, PRL 100, 047206 (2008)
[1.6] J. M. D. Coey et al., Nature Materials, 4 (2005), 173
[1.7] Y.Igasaki and H.Saito,Thin Solid Films ,223.199(1991)
[1.8] S.-s.Yan et al.,J.Phys.Condens.Matter 18,10,469(2006)
[1.9] A.Chattopadhyay et al., PRL. 87, 227202(2001)
[1.10] Z. L. Lu and J. C. A. Huang , APL ,95 ,102501 (2009)

第二章
[2.1] J.C.A. Huang，Ph.D. Thesis，Univ. of Illinois
[2.2] B.Heinrich，J.A.C.Bland，Ultrathin Magnetic Structure I，Springer-Verlag,New York (1994)
[2.3] E.Bauer，Appl. Surf. Sci. 11/12，479(1982)
[2.4] B.Heinrich，J.A.C.Bland，Ultrathin Magnetic Structure I，Springer-Verlag,New York (1994)
[2.5] B.Dodson,Phys.Rev.B，36，6288(1987)
[2.6] W.Wulfhekel,F.Zavaliche，R.Hertel,S.Bodea,G.Steierl，G.Liu and J.Kirschner，Phys.Rev.B 68,144416(2003)
[2.7] P.J.Berlowitz，J.W.He and D.W.Goodman，Surf.Sci.231，315 (1990)
[2.8] T. Deitl¸and H. Ohno et al.，Science 287 (2000) 1019
[2.9] C. Zener et al.，Phys. Rev. 81 (1950) 440
[2.10] H.Akai et al., Phys. Rev. Lett.,81(1998),3002
[2.11] J.Konig et al., Phys. Rev. Lett.,84(2000),5628
[2.12] J.Konig et al., Phys. Rev. Lett.,86 2001),563731
[2.13] V.I.Litvinov et al，Phys.Rev.Lett.86(2001)5593
[2.14] M.Berciu et al，Phys.Rev.Lett.86(2001)107203
[2.15] J. M. D. Coey et al., Nature Materials, 4 (2005),173

第三章
[3.1] See e. g. “Molecular Beam Epitaxy”，ed. by M. A.Herman
and H.Sitter (Berlin Springer，1989)
[3.2] P. K. Larsen and P. J. Dobson，Reflection High‐Energy
Electron Diffraction and Reflection Electron Imaging of
Surface， NATO ASI Series
[3.3] Soshin Chikazumi and Stanley H. Charap “Physics of
Magnetism”(1972)
[3.4] 國立台灣大學物理學系，楊鴻昌教授，科學新知，6 期12 卷
1991 年，p72-p79
[3.5] 施敏，半導體元件物理與製作技術,p23-p47,(1997)
[3.6] D .C .Koningsberger and R .Prins，X‐ray Absorption
principles，applications，techniques of EXAFS，SEXAFS and
XANES (1988) 574
[3.7] J.J.Rehr and R.C.Albers，Rev. Mod. Phys. 72 (2000) 621

第四章
[4.1] B.E.Sernelius , K.F.Berggern , Phys. Rev. B 37, 10244
-10248 (1988)
[4.2] X.C. Liu et al. Appl. Phys. Lett., 88 (2006), 252503
[4.3] 邱淑琳 國立成功大學物理研究所(2007)
[4.4] Kevin R. Kittilstved and Daniel R. Gamelin et al.Phys.
Rev. Lett. 97(2006) 037203
[4.5] Z. L. Lu and J. C. A. Huang , APL ,95 ,102501 (2009)