電漿增強式原子層沈積法成長摻雜氮原子之P型氧化鋅薄膜特性分析

本研究以射頻電漿增強式原子層沈積系統成長氮摻雜P型氧化鋅薄膜，藉由改變成長溫度(75 – 250 oC)、電漿之射頻功率(0 – 200 W)、氨氣(5 – 50 sccm)的流量，來探討其對氧化鋅薄膜之影響。電漿系統可將NH3氣體分解成N及NH以利於取代氧原子。此P型氧化鋅薄膜被成長於藍寶石(sapphire)基板上，厚度約為110 nm。將所成長之氧化鋅薄膜進行800oC - 900oC熱退火處理，藉由退火處理可打斷氮原子與氫離子的鍵結，讓氮原子佔據氧原子空缺形成受體(acceptor)，提高P型氧化鋅濃度。本實驗利用霍爾量測、X光繞射分析儀、光激螢光量測系統及X射線光電子能譜分析儀來進行薄膜之光電分析，結晶狀態及鍵結型態。由霍爾量測結果可知，在成長溫度100oC、NH3流量10sccm及射頻功率100瓦沉積之薄膜，經過900oC熱處理後可得最高之電洞濃度4.041017 cm-3及最低的電阻值52.10 -cm與移動率0.55 cm2/Vs之薄膜。藉由X光繞射分析儀的量測可發現當NH3流量變大時，其(101)晶相之角度會往小角度偏移，主要是因為N2分子佔據氧原子空缺所造成；另外X光繞射分析也可看出回火後之氮摻雜氧化鋅薄膜其(101) 晶相角度較未摻雜之氧化鋅大，是因為鋅與氮的鍵結比鋅與氧的鍵結弱之關係。氮摻雜之P型氧化鋅薄膜發光特性則可藉由低溫光激螢光發光量測所得知，於紫外光波段發現了3.361 eV的峰值，是由受體束縛激子(neutral acceptor-bound exciton, DoX)所造成、3.311 eV 的自由電子到受體之轉換(free electron to acceptor, FA)、以及3.255 eV的施子受子對(donor-acceptor pair)發光，另外在3.180 eV 有一微弱的峰值是由施子受子對的縱模光聲子發光所造成的。而自由電子到受體之轉換與施子受子對的發光被假設為氧化鋅薄膜中的氮原子占據氧缺陷所造成的。最後利用X射線光電子能譜分析儀可以有力的證明N原子與氧化鋅薄膜之鍵結型態，發現在397.5 eV的地方有一峰值，是由氮原子占據氧缺陷所造成的。

關鍵字

P型氧化鋅；原子層沉積；光激發螢光發光；氮氣

並列摘要

Radio frequency plasma enhanced atomic layer deposition (RF-PEALD) technique was used to deposit nitrogen-doped (N-doped) p-type ZnO thin films on sapphire substrate at 75 - 250oC with an RF power of plasma source 0 - 200 W and NH3 flow rate of 5 – 50 sccm. Ammonia (NH3) gas, decomposed by the plasma to form N, NH and NH2, was used as the source of nitrogen and the flow rate of it was varied. The N-doped ZnO was deposited on sapphire substrate, and the thickness of 110 nm. Post-annealing treatment was conducted to remove the hydrogen ions in the as-grown films at 800oC to 900oC by a rapid thermal annealing (RTA) system. N-doped ZnO films were characterized by Hall measurements, X-ray diffraction (XRD), low temperature photoluminescence (LTPL) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Hall measurements showed the highest hole concentration of 4.041017 cm-3, the lowest resistivity of 52.10 -cm, and the hole mobility of 0.55 cm2/V-s for N-doped ZnO, which was fabricated at 100oC substrate temperature 、with RF power of 100W and NH3 flow rate of 10sccm. Besides, the crystallographic structures and bonding configurations obtained from the XRD results demonstrated the formation of No acceptors by substituting N atom for O sublattice or N2 for O atom. The LTPL spectra for N-doped p-type ZnO films exhibited the emissions ascribed to the neutral donor bound excitons (DoX) at 3.361 eV, free electrons to acceptor (FA) transition at 3.311 eV, and the donor-acceptor pair (DAP) recombination at 3.255 eV with a weaker peak at 3.180 eV assigned to the longitudinal optical (LO) phonons. The appearance of both FA and DAP transitions related emissions are suggested to be associated with the replacement of N atom for O atom (No) in ZnO. XPS results indicated that a part of N substrate O atom to form the accepter-like defects. The binding energy of No could be established at 397.5 eV.

並列關鍵字

p-type ZnO ； ALD ； PL ； NH3

參考文獻

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電漿增強式原子層沈積法成長摻雜氮原子之P型氧化鋅薄膜特性分析

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