Dielectric Force Microscopy: Imaging Charge Carriers in Nanomaterials without Electrical Contacts

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	Dielectric Force Microscopy: Imaging Charge Carriers in Nanomaterials without Electrical Contacts
	Zhang, J(张杰); Lu, W(卢威); Li, YS; Cai, JH(蔡金华); Chen, LW(陈立桅)
刊名	ACCOUNTS OF CHEMICAL RESEARCH
	2015
卷号	48 期号:7 页码:9
通讯作者	Chen, LW (陈立桅)
英文摘要	CONSPECTUS: Nanomaterials are increasingly used in electronic, optoelectronic, bioelectronic, sensing, and energy nanodevices. Characterization of electrical properties at nanometer scales thus becomes not only a pursuit in basic science but also of widespread practical need. The conventional field-effect transistor (PET) approach involves making electrical contacts to individual nanomaterials. This approach faces serious challenges in routine characterization due to the small size and the intrinsic heterogeneity of nanomaterials, as well as the difficulties in forming Ohmic contact with nanomaterials. Since the charge carrier polarization in semiconducting and metallic materials dominates their dielectric response to external fields, detecting dielectric polarization is an alternative approach in probing the carrier properties and electrical conductivity in nanomaterials. This Account reviews the challenges in the electrical conductivity characterization of nanomaterials and demonstrates that dielectric force microscopy (DFM) is a powerful tool to address the challenges. DFM measures the dielectric polarization via its force interaction with charges on the DFM tip and thus eliminates the need to make electrical contacts with nanomaterials. Furthermore, DFM imaging provides nanometer-scaled spatial resolution. Single-walled carbon nanotubes (SWNTs) and ZnO nanowires are used as model systems. The transverse dielectric permittivity of SWNTs is quantitatively measured to be similar to 10, and the differences in longitudinal dielectric polarization are exploited to distinguish metallic SWNTs from semiconducting SWNTs. By application of a gate voltage at the DFM tip, the local carrier concentration underneath the tip can be accumulated or depleted, depending on charge carrier type and the density of states near the Fermi level. This effect is exploited to identify the conductivity type and carrier type in nanomaterials. By making comparison between DFM and PET measurements on the exact same SWNTs, it is found that the DFM gate modulation ratio, which is the ratio of DFM signal strengths at different gate voltage, is linearly proportional to the logarithm of PET device on/off ratio. A Drude-level model is established to explain the semilogarithmic correlation between DFM gate modulation ration and PET device on/off ratio and simulate the dependence of DFM force on charge carrier concentration and mobility. Future developments towards DFM imaging of charge carrier concentration or mobility in nanomaterials and nanodevices can thus be expected.
收录类别	SCI
语种	英语
公开日期	2016-05-03
内容类型	期刊论文
源URL	[http://ir.sinano.ac.cn/handle/332007/3346]
专题	苏州纳米技术与纳米仿生研究所_纳米研究国际实验室_陈立桅团队
推荐引用方式 GB/T 7714	Zhang, J,Lu, W,Li, YS,et al. Dielectric Force Microscopy: Imaging Charge Carriers in Nanomaterials without Electrical Contacts[J]. ACCOUNTS OF CHEMICAL RESEARCH,2015,48(7):9.
APA	Zhang, J,Lu, W,Li, YS,Cai, JH,&Chen, LW.(2015).Dielectric Force Microscopy: Imaging Charge Carriers in Nanomaterials without Electrical Contacts.ACCOUNTS OF CHEMICAL RESEARCH,48(7),9.
MLA	Zhang, J,et al."Dielectric Force Microscopy: Imaging Charge Carriers in Nanomaterials without Electrical Contacts".ACCOUNTS OF CHEMICAL RESEARCH 48.7(2015):9.