Review of flexible and transparent thin-film transistors based on zinc oxide and related materials

Flexible and transparent electronics enters into a new era of electronic technologies.Ubiquitous applications involve wearable electronics,biosensors,flexible transparent displays,radio-frequency identifications(RFIDs),etc.Zinc oxide(ZnO) and relevant materials are the most commonly used inorganic semiconductors in flexible and transparent devices,owing to their high electrical performances,together with low processing temperatures and good optical transparencies.In this paper,we review recent advances in flexible and transparent thin-film transistors(TFTs) based on ZnO and relevant materials.After a brief introduction,the main progress of the preparation of each component(substrate,electrodes,channel and dielectrics) is summarized and discussed.Then,the effect of mechanical bending on electrical performance is highlighted.Finally,we suggest the challenges and opportunities in future investigations.     

氧化锌基材料、异质结构及光电器件

Ⅱ-Ⅵ族直接带隙化合物半导体氧化锌(ZnO)的禁带宽度为3.37 eV,室温下激子束缚能高达60 meV,远高于室温热离化能(26 meV),是制造高效率短波长探测、发光和激光器件的理想材料。历经10年的发展,ZnO基半导体的研究在薄膜生长、杂质调控和器件应用等方面的研究获得了巨大的进展。本文主要介绍了以国家"973"项目(2011CB302000)研究团队为主体,在上述方面所取得的研究进展,同时概述国际相关研究,主要包括衬底级ZnO单晶的生长,ZnO薄膜的同质、异质外延,表面/界面工程,异质结电子输运性质、合金能带工程,p型掺杂薄膜的杂质调控,以及基于上述结果的探测、发光和激光器件等的研究进展。迄今为止,该团队已经实现了薄膜同质外延的二维生长、硅衬底上高质量异质外延、基于MgZnO合金薄膜的日盲紫外探测器、可重复的p型掺杂、可连续工作数十小时的同质结紫外发光管以及模式可控的异质结微纳紫外激光器件等重大成果。本文针对这些研究内容中存在的问题和困难加以剖析并探索新的研究途径,期望能对ZnO材料在未来的实际应用起到一定的促进作用。     

氧化锌基材料、异质结构及光电器件

Ⅱ-Ⅵ族直接带隙化合物半导体氧化锌（ZnO）的禁带宽度为3.37 eV,室温下激子束缚能高达60 meV,远高于室温热离化能（26 meV）,是制造高效率短波长探测、发光和激光器件的理想材料。历经10年的发展,ZnO基半导体的研究在薄膜生长、杂质调控和器件应用等方面的研究获得了巨大的进展。本文主要介绍了以国家“973”项目（2011CB302000）研究团队为主体,在上述方面所取得的研究进展,同时概述国际相关研究,主要包括衬底级ZnO单晶的生长,ZnO薄膜的同质、异质外延,表面/界面工程,异质结电子输运性质、合金能带工程,p型掺杂薄膜的杂质调控,以及基于上述结果的探测、发光和激光器件等的研究进展。迄今为止,该团队已经实现了薄膜同质外延的二维生长、硅衬底上高质量异质外延、基于MgZnO合金薄膜的日盲紫外探测器、可重复的p型掺杂、可连续工作数十小时的同质结紫外发光管以及模式可控的异质结微纳紫外激光器件等重大成果。本文针对这些研究内容中存在的问题和困难加以剖析并探索新的研究途径,期望能对ZnO材料在未来的实际应用起到一定的促进作用。     

Direct ZnO X-Ray Detector with Tunable Sensitivity

Direct ZnO x-ray detectors with tunable sensitivity are realized by delicately controlling the oxygen flux during the sputtering deposition process. The photocurrents induced by x-rays from a 40 kV x-ray tube with a Cu anode increase apparently as the oxygen flux decreases, which is attributed to the introduction of V_o detects.By introducing V_o defects, the annihilation rate of the photo-generated electron-hole pairs will be greatly slowed down, leading to a remarkable photoconductive gain. This finding informs a novel way to design the x-ray detectors based on abundant oxide materials.     

Optical simulation of CsPbI3/TOPCon tandem solar cells with advanced light management

Monolithic perovskite/Si tandem solar cells (TSCs) have experienced rapid development in recent years, demonstrating its potential to exceed the Shockley-Queisser limit of single junction Si solar cells. Unlike typical organic-inorganic hybrid perovskite/silicon heterojunction TSCs, here we propose CsPbI₃/TOPCon TSC, which is a promising architecture in consideration of its pleasurable thermal stability and good compatibility with current PERC production lines. The optical performance of CsPbI₃/TOPCon TSCs is simulated by the combination of ray-tracing method and transfer matrix method. The light management of the CsPbI₃/TOPCon TSC begins with the optimization of the surface texture on Si subcell, indicating that a bifacial inverted pyramid with a small bottom angle of rear-side enables a further minimization of the optical losses. Current matching between the subcells, as well as the parasitic absorption loss from the front transparent conductive oxide, is analyzed and discussed in detail. Finally, an optimized configuration of CsPbI₃/TOPCon TSC with a 31.78% power conversion efficiency is proposed. This work provides a practical guidance for approaching high-efficiency perovskite/Si TSCs.     

Enhanced photoresponse performance in Ga/Ga_2O_3 nanocomposite solar-blind ultraviolet photodetectors

In the present work, we explore the solar-blind ultraviolet(UV) photodetectors(PDs) with enhanced photoresponse,fabricated on Ga/Ga_2O_3 nanocomposite films. Through pre-burying metal Ga layers and thermally post-annealing the laminated Ga2 O3/Ga/Ga_2O_3 structures, Ga/Ga_2O_3 nanocomposite films incorporated with Ga nanospheres are obtained. For the prototype PD, it is found that the photocurrent and photoresponsivity will first increase and then decrease monotonically with the thickness of the pre-buried Ga layer increasing. Each of all PDs shows a spectrum response peak at 260 nm, demonstrating the ability to detect solar-blind UV light. Adjustable photoresponse enhancement factors are achieved by means of the surface plasmon in the nanocomposite films. The PD with a 20 nm thick Ga interlayer exhibits the best solar-blind UV photoresponse characteristics with an extremely low dark current of 8.52 p A at 10-V bias, a very high light-to-dark ratio of ～ 8 × 10~5, a large photoresponsivity of 2.85 A/W at 15-V bias, and a maximum enhancement factor of ～ 220. Our research provides a simple and practical route to high performance solar-blind UV PDs and potential applications in the field of optoelectronics.     

氧化物半导体柔性电子学研究进展

柔性电子学器件在未来消费电子领域有巨大的应用前景,更是消费升级和社会进步的必然需求,在可穿戴传感、柔性显示、电子皮肤和可植入医疗等领域有着广泛的应用前景。柔性透明高压二极管器件在构建一体化光伏系统和自供电可穿戴设备的能源管理电路中有着巨大的应用潜力。文章首先设计并制作了一种新颖的柔性透明Zn O场效应二极管,其整流比可高达108,漏电流低至10-15A/μm,且制备工艺和普通TFT完全兼容。通过引入特定尺寸的错排(offset)区域,进一步制备了击穿电压最高可达150 V的柔性透明高压二极管;利用4个单元器件组合成柔性高压全波整流电路,成功地将摩擦纳米发电机产生的高压交流电整流为直流电,存储到超级电容器中。柔性光电探测器因具有轻便耐用、柔软便携、可与非平面组织贴合等独特优势,逐渐成为光电探测技术发展的一个新方向。通过微量调控生长过程中的氧流量,系统研究了柔性非晶Ga₂O₃日盲紫外探测器和X射线探测器的性能与材料制备过程中氧分压的对应关系,实现了对器件响应度和响应速度的调控,并给出了相应的物理模型;通过器件结构的设计与材料物性的调控,器件的性能...