Intrinsic photoluminescence from low temperature deposited zinc oxide thin films as a function of laser and thermal annealing
Intrinsic photoluminescence from low temperature deposited zinc oxide thin films as a function of laser and thermal annealing
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DOI：
10.1088/0022-3727/46/9/095305
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
C. Tsakonas;W. Cranton;Flora M. Li;K. Abusabee;A. Flewitt;D. Koutsogeorgis;R. Ranson
中科院分区：
文献类型：
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作者：
C. Tsakonas;W. Cranton;Flora M. Li;K. Abusabee;A. Flewitt;D. Koutsogeorgis;R. Ranson
采用激光退火、热退火和快速热退火对高靶利用率溅射沉积的60 nm ZnO薄膜进行了不同退火工艺对低温沉积ZnO薄膜改性的研究。使用KrF准分子激光器（λ = 248 nm）在高达318 mJ cm−2的能量密度范围内进行的单脉冲激光退火证明了内部薄膜微结构和发光特性的可控深度改性，而不会因高温热和RTA工艺而产生薄膜退化。光致发光（PL）性质表明，与缺陷相关的深能级发射（DLE，450-750 nm，2.76-1.65 eV）与激子近带边发射（NBE，381 nm，3.26 eV）的比率与工艺参数直接相关。热处理和快速热处理导致由与过量氧相关的缺陷主导的强可见橙子/红色DLE PL（具有在590 nm，2.10 eV和670 nm，1.85 eV处的峰）的演变。在较高的温度下，一个绿色/黄色的发射（530 nm，2.34 eV）的外观表示的主要辐射传输机制的过渡。相比之下，激光处理去除了与DLE相关的缺陷，并产生了具有强烈NBE发光的膜，这与观察到的大晶粒（25-40 nm）的形成相关。
An investigation into the modification of low temperature deposited ZnO thin films by different annealing processes has been undertaken using laser, thermal and rapid thermal annealing of 60 nm ZnO films deposited by high-target-utilization sputtering. Single-pulse laser annealing using a KrF excimer laser (λ = 248 nm) over a range of fluences up to 318 mJ cm−2 demonstrates controlled in-depth modification of internal film microstructure and luminescence properties without the film degradation produced by high temperature thermal and RTA processes. Photoluminescence (PL) properties show that the ratio of defect related deep level emission (DLE, 450–750 nm, 2.76–1.65 eV) to excitonic near band-edge emission (NBE at 381 nm, 3.26 eV) is directly correlated to processing parameters. Thermal and rapid thermal processing results in the evolution of a strong visible orange/red DLE PL (with peaks at 590 nm, 2.10 eV and 670 nm, 1.85 eV) dominated by defects related to excess oxygen. At higher temperatures, the appearance of a green/yellow emission (530 nm, 2.34 eV) indicates a transition of the dominant radiative transfer mechanism. In contrast, laser processing removes defect related DLE and produces films with intense NBE luminescence, correlated to the observed formation of large grains (25–40 nm).