新型聚合物半导体薄膜及其场效应晶体管的研究

叶建春; 周礼照; 李文武; 欧阳威

doi:10.3969/j.issn.1000-5641.201922006

新型聚合物半导体薄膜及其场效应晶体管的研究

doi: 10.3969/j.issn.1000-5641.201922006

1.
华东师范大学物理与电子科学学院纳光电集成与先进装备教育部工程研究中心, 上海　200062
2.
华东师范大学物理与电子科学学院极化材料与器件教育部重点实验室, 上海　200241

基金项目: 国家自然科学基金( 61504042，61771198); 上海市自然科学基金(17ZR1447000); 中央高校基本科研业务费专项资金

详细信息

通讯作者:
欧阳威, 男, 副教授, 硕士生导师, 研究方向为纳米材料与器件. E-mail: ouyangwei@phy.ecnu.edu.cn

中图分类号: O472+.4
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出版历程
- 收稿日期: 2019-03-19
- 网络出版日期: 2019-12-25
- 刊出日期: 2020-01-01

Novel polymer semiconductor films and related field effect transistor devices

1.
Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, School of Physics and Electronic Science, East China Normal University, Shanghai　200062, China
2.
Key Laboratory of Polar Materials and Devicesn, Ministry of Education, School of Physics and Electronic Science, East China Normal University, Shanghai　200241

摘要

摘要: 以新型的有机聚合物半导体(DPPTTT(poly(3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione) thieno [3,2-b] thiophene))为研究对象, 利用溶液法制备了有机半导体薄膜并进行了一系列表征. 发现半导体薄膜的厚度、表面粗糙度和拉曼峰强度均随溶液浓度和转速呈规律性变化. 以该材料作为半导体活性层制备了 p 型有机场效应晶体管, 发现当沟道长度降低到50 μm时, 器件的有效载流子迁移率最高, 达到0.12 cm²/Vs; 同时观察到随着沟道长度的降低, 载流子迁移率与阈值电压都有增大的趋势, 这与普遍观察到的短沟道效应相反. 这些研究内容或许可以为更好地理解有机场效应晶体管及器件物理提供新的观点.
- 有机场效应晶体管 /
- 聚合物半导体 /
- 溶液法 /
- 短沟道效应 /
- 接触电阻
Abstract: Thin films using a novel organic polymer semiconductor (DPPTTT(poly(3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione) thieno [3,2-b] thiophene)) were prepared by a solution process and characterized through different techniques. It was found that the thickness, surface roughness, and Raman peak strength of the semiconductor films changed with the solution concentration and rotation rate. The polymer semiconductor was used to prepare the active layer for p-type organic field effect transistors; with these, the influence of channel length on critical transistor parameters (i.e., carrier mobility and threshold voltage) was studied. It was found that the effective carrier mobility was the highest at 0.12 cm²/Vs when the channel length was reduced to 50 μm. With a decrease in channel length, both carrier mobility and threshold voltage tended to increase, which was contrary to the short channel effect. This paper may provide new perspectives for better understanding the physics of field effect transistor devices.
- organic field effect transistor /
- polymer semiconductor /
- solution process /
- short channel effect /
- contact resistance

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图 1 器件结构和DPPTTT的分子结构式，沟道宽度(W)为1 000 μm, 沟道长度(L) 为 50~300 μm

Fig. 1 The schemed structure of the device and the constitutional molecular structure of DPPTTT, the channel width (W) is 1 000 μm and the channel length (L) is 50~300 μm

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图 2 不同工艺参数下得到的有机半导体薄膜的表面SEM图: (a) 样品浓度为10 mg/mL, 转速为2 000 r/min; (b) 样品浓度为10 mg/mL, 转速为4 000 r/min

Fig. 2 SEM top views of organic semiconductor thin films with various deposition parameters: (a) Solution concentration of 10 mg/mL, rotation rate of 2 000 r/min; (b) solution concentration of 10 mg/mL, rotation rate of 4 000 r/min

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图 3 BCB薄膜和不同工艺参数下得到的有机半导体薄膜的AFM图: (a) 转速为2 000 r/min的BCB薄膜; (b) 样品浓度为10 mg/mL, 转速为2 000 r/min; (c) 样品浓度为10 mg/mL, 转速为4 000 r/min;(d) 样品浓度为5 mg/mL, 转速为2 000 r/min; (e) 样品浓度为5 mg/mL, 转速为4 000 r/min; (f) 样品浓度为5 mg/mL, 转速为8 000 r/min

Fig. 3 AFM graphs of BCB thin films and DPPTTT thin films with various parameters: (a) BCB thin film made by 2 000 r/min; (b) solution concentration of 10 mg/mL, rotation rate of 2 000 r/min; (c) solution concentration of 10 mg/mL, rotation rate of 4 000 r/min; (d) solution concentration of 5 mg/mL, rotation rate of 2 000 r/min; (e) solution concentration of 5 mg/mL, rotation rate of 4 000 r/min; (f ) solution concentration of 5 mg/mL, rotation rate of 8 000 r/min

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图 4 不同溶液浓度和转速下得到的DPPTTT薄膜粗糙度的比较

Fig. 4 Roughness of DPPTTT thin films deposited by various solution concentrations and rotation rates

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图 5 不同工艺参数下得到的有机半导体薄膜的侧面SEM图: (a) 样品浓度为10mg/mL, 转速为2 000 r/min; (b) 样品浓度为10 mg/mL, 转速为2 000 r/min; (c) 样品浓度为5mg/mL, 转速为2 000 r/min

Fig. 5 SEM side views of organic semiconductor thin films with various deposition parameters: (a) solution concentration of 10 mg/mL, rotation rate of 2 000 r/min; (b) solution concentration of 10 mg/mL, rotation rate of 4 000 r/min; (c) solution concentration of 5 mg/mL, rotation rate of 2 000 r/min

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图 6 DPPTTT薄膜厚度与浓度和转速的关系图

Fig. 6 The thickness of DPPTTT thin films with respective to various concentrations and rotation rates

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图 7 氧化硅片衬底、BCB薄膜和不同工艺参数下得到的DPPTTT薄膜的拉曼散射谱图

Fig. 7 Raman spectrum of Si/SiO₂, BCB thin film, and DPPTTT thin films with various deposition parameters

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图 8 不同沟道长度的器件的转移特性曲线(L = 50 ~ 300 μm): (a) 源漏电流绝对值(对数坐标)关于栅源电压的变化曲线; (b) 源漏电流的平方根($\sqrt {{I_{{\rm{DS}}}}} $)关于栅源电压的变化曲线

Fig. 8 Transfer characteristics of devices with various channel lengths from 50 to 300 μm: (a) absolute drain current in logarithmic scale versus gate voltage; (b) square root of drain current ($\sqrt {{I_{{\rm{DS}}}}} $) versus gate voltage

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图 9 场效应迁移率和阈值电压随沟道长度的变化关系, 沟道宽度为1 000 μm

Fig. 9 Field effect mobility (μ _FE) and threshold voltage (V _th) as a relationship of channel length (L); the channel width (W) is 1 000 μm and the channel length (L) is 50~300 μm

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图 10 亚阈值摆幅SS和缺陷密度 N 随沟道长度的变化关系, 沟道长度L = 50 ~ 300 μm

Fig. 10 Subthreshold swing (SS) and interface trap density N as a function of channel length, the channel length L is from 50 μm to 300 μm.

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表 1 不同参数下得到的DPPTTT薄膜的拉曼位移和拉曼峰强度

Tab. 1 Raman shift and peak intensity of DPPTTT thin films with various deposition parameters

样品	拉曼位移/cm^–1	拉曼峰强度
DPPTTT-10 mg/mL-BCB-2 000 r/min	1 550	1 034
DPPTTT-10 mg/mL-BCB-4 000 r/min	1 547	1 455
DPPTTT-5 mg/mL-2 000 r/min	1 546	425
DPPTTT-5 mg/mL-4 000 r/min	1 549	287
DPPTTT-5 mg/mL-8 000 r/min	1 545	243

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