利用射頻磁控共濺鍍系統沉積鋁+氮共摻雜之氧化鋅薄膜

Aluminum-nitride codoped zinc oxide films prepared using a radio-frequency magnetron cosputtering system

許加昇(Chia-Sheng Sheu)

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2007年)

摘要

本研究利用射頻磁控共濺鍍系統，以氧化鋅以及氮化鋁為共濺鍍靶材，藉由改變施加在氧化鋅及氮化鋁靶材之射頻功率，製作並控制具有不同濃度的鋁+氮共摻雜之氧化鋅薄膜，並在氮氣環境下進行後續熱處理製程，藉以活化摻雜在薄膜中的受體離子，製作p型氧化鋅薄膜。
研究結果顯示，在室溫下所沉積之具有不同鋁原子濃度之共濺鍍薄膜呈現n型的導電型態，且薄膜的電子濃度隨著鋁原子濃度的上升而上升，當鋁原子理論值含量[Al/(Zn+Al)]為60%，薄膜的載子濃度則有明顯下降的趨勢。而根據共濺鍍薄膜的結晶特性量測結果，可以發現，薄膜之結晶性從未摻雜氧化鋅薄膜的C軸ZnO(002)優選成長方向逐漸轉變為以ZnO (001)成長方向為主。當共濺鍍鋁原子含量達60%時，此時薄膜受到大量氮化鋁共濺鍍的影響，形成非晶的結構特性，進而大幅劣化薄膜的電特性。為了有效活化鋁+氮共摻雜氧化鋅薄膜中的受體離子，獲得p型氧化鋅薄膜，本研究針對於室溫環境下鋁原子摻雜濃度之理論值為10%的共濺鍍薄膜，藉由適當溫度的熱處理製程，可以使薄膜的電特性轉變為p型的導電型態，從x光繞射光譜圖可以發現，薄膜中有氮化鋅的結晶相產生，顯示此時薄膜中的鋅原子有氮化(nitrification)的現象，此外，根據光激發螢光譜圖及x光光電子能譜圖的量測結果也可以發現，熱處理製程可以有效的活化共濺鍍薄膜中的氮離子形成N-Zn化學鍵結，使得薄膜呈現p型的氧化鋅導電型態，而當熱處理條件為400oC、氮氣環境熱處理30分鐘，此時鋁+氮共摻雜氧化鋅薄膜具有優異的p型導電特性

並列摘要

Al-N codoped zinc oxide films were prepared using a radio-frequency magnetron cosputtering system using AlN and ZnO targets at room temperature. The as-deposited cosputtered films at various theoretical atomic ratios [Al / (Al + Zn) at.%] showed n-type conductive behavior in spite of the N atoms exceeding that of the Al dopants, indicating that the N-related acceptors were still inactive. The crystalline structure was obviously correlated with the cosputtered AlN contents and eventually evolved into an amorphous structure for the Al-N codoped ZnO film at a theoretical Al doping level reaching 60%. With an adequate post-annealing treatment, the N-related acceptors were effectively activated and the p-type ZnO conductive behavior achieved. The appearance of the Zn3N2 phase in the X-ray diffraction pattern of the annealed Al-N codoped ZnO film provided evidence of N impurity activation. The red-shift of the shallow level transition and the apparent suppression of the oxygen-related deep level emission investigated from the PL spectrum measured at room temperature were concluded to be influenced by these activated N-related acceptors. In addition, the activation of the N acceptors denoted as N-Zn bond and the chemical bond related to the Zn3N2 crystalline structure were also observed from the associated XPS spectra.

參考文獻

【2】 K. H. Choi, J. Y. Kim, Y. S. Lee and H. J. Kim, “ITO/Ag/ITO multilayer films for the application of a very low resistance transparent electrode”, Thin Solid Films, 341, p. 152 (1999).

【3】 B. Z. Dong, G. J. Fang, J. F. Wang, W. J. Guan and X. Z. Zhao, “Effect of thickness on structural, electrical, and optical properties of ZnO : Al films deposited pulsed laser deposition”, J. Appl. Phys ,101, p. 033713 (2007).

G. Schoer and J. Mueller, “Second order optical nonlinearity of ZnO/ZnO:Al bilayers deposited on glass by low temperature radio frequency sputtering”, Appl. Phys. Lett, 90, p. 181110 (2007).

【6】 D. E. Pugel, R. D. Vispute, S. S. Hullavarad, T. Venkatesan and B. Varughese, “ Oxygen-dependent phosphorus networking in ZnO thin films grown by low temperature rf sputtering”, J.Appl. Phys ,101, p. 063538 (2006).

【7】 M. L. Tu, Y. K. Su and C. Y. Ma, “ Nitrogen-doped p-type ZnO films prepared from nitrogen gas radio frequency magnetron sputtering”, J. Appl. Phys , 100, p. 053705 (2006).