ZnO薄膜发光器件的电抽运随机激射:随机性的抑制  

Suppression of randomness of electrically pumped random lasing from light-emitting devices based on ZnO films

作　　者：纪然 蒋书明 夏程涛 杨德仁[1,2] 马向阳 JI Ran;JIANG Shuming;XIA Chengtao;YANG Deren;MA Xiangyang(State Key Laboratory of Silicon and Advanced Semiconductor Materials,Zhejiang University,Hangzhou 310027,China;Shangyu Institute of Semiconductor Materials,Shaoxing 312300,China)

机构地区：[1]浙江大学,硅及先进半导体材料国家重点实验室,杭州310027 [2]上虞半导体材料研究中心,绍兴312300

出　　处：《物理学报》2025年第4期128-137,共10页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2018YFB2200102)资助的课题.

摘　　要：通过以大晶粒水热ZnO薄膜作为发光层并加以恰当图案化处理的策略,显著抑制了基于ZnO薄膜的金属-绝缘体-半导体(MIS)结构发光器件的电抽运随机激射的随机性.采用激光直写光刻工艺,先将硅衬底上的晶粒大小超过500 nm的水热ZnO薄膜图案化为大量的小方块(Block)和“街道(Street)”,然后制备基于上述图案化ZnO薄膜的MIS结构(Au/SiO_(2)/ZnO)发光器件(light-emitting device,LED).研究表明:在相同的注入电流下,基于图案化ZnO薄膜的发光器件比基于未图案化ZnO薄膜的发光器件具有更少的随机激射模式;且前者随Block边长的减小而具更少的激射模式,同时其最强激射模式的波长在更窄的范围内波动.值得指出的是:在适当的条件(小注入电流和小Block边长)下,基于图案化水热ZnO薄膜的发光器件还可产生单模随机激射.此外,对比研究还表明:基于大晶粒水热ZnO薄膜的LED比基于小晶粒溅射ZnO薄膜的LED具有更小的激射阈值电流,且在同样的注入电流下具有更少的激射模式和更高的激射光功率.关于上述结果背后的物理机制,分析指出:对基于图案化ZnO薄膜的发光器件而言,一方面由于单个Block内ZnO薄膜中的晶粒和晶界数量有限,光多重散射被严重削弱,那些能够通过光多重散射获得净光增益而产生随机激射的路径与ZnO薄膜未经图案化处理的情形相比要少得多.另一方面,由于单个Block空间有限,不同激射模式之间的增益竞争使得空间上重叠较大的激射模式不能同时存在.由于上述两方面的原因,随着Block边长的减小,发光器件随机激射的模式会变得更少.此外,Block之间的光学耦合效应会加剧单个Block内部激射模式之间的增益竞争,从而进一步减少发光器件的随机激射模式.In this work,the randomness of electrically pumped random laser(RL)from ZnO-based metal-insulatorsemiconductor(MIS)structured light-emitting device(LED)is significantly suppressed,by using appropriately patterned hydrothermal ZnO film with large crystal grains as the light-emitting layer.The hydrothermal ZnO film on silicon substrate,with the crystal grains sized over 500 nm,is first patterned into a number of square blocks separated by streets by using laser direct writing photolithography.Based on such a patterned ZnO film,the MIS(Au/SiO_(2)/ZnO)structured LEDs are prepared on silicon substrates.Under the same injection current,the LED with the patterned ZnO film exhibits much fewer RL modes than that with the non-patterned ZnO film and,moreover,the former displays ever-fewer RL modes with the the decrease of block size.Besides,the wavelength of the strongest RL mode from the LED with the patterned ZnO film fluctuates in a much narrower range than that with the non-patterned ZnO film.It is worth mentioning that the LED with the patterned hydrothermal ZnO film can even be pumped into the single-mode RL under the desirable conditions such as low injection current and small patterned blocks.Moreover,the comparative investigation indicates that the LED with the large-grain hydrothermal ZnO film exhibits the smaller RL threshold current than that with the smallgrain sputtered ZnO film,and the former has fewer RL modes and a higher output lasing power than the latter under the same injection current.As for the physical mechanism behind the aforementioned results,it is analyzed as follows.Regarding the LED with the patterned ZnO film,on the one hand,due to the limited numbers of crystal grains and grain boundaries within a single block,the multiple optical scattering is remarkably suppressed.Then,the paths through which the net optical gain and therefore the lasing action can be achieved via multiple optical scattering are much fewer than those in the case of the non-patterned ZnO film.On the other hand,due to optical

关 键 词：水热ZnO 薄膜 发光器件 随机激射 图案化 随机性的抑制 

分 类 号：TN3[电子电信—物理电子学]