Correlation of p-doping in CVD Graphene with Substrate Surface Charges.
Correlation of p-doping in CVD Graphene with Substrate Surface Charges.
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DOI：
10.1038/srep22858
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发表时间：
2016-03-09
影响因子：
4.6
通讯作者：
Klein N
中科院分区：
文献类型：
--
作者：
Goniszewski S;Adabi M;Shaforost O;Hanham SM;Hao L;Klein N
测量了在大面积化学气相沉积（CVD）石墨烯场效应晶体管结构（gFET）中表现出的p掺杂水平与在CVD石墨烯转移之前由对二氧化硅（SiO2）衬底的各种表面处理产生的残余电荷之间的相关性。从未处理的热氧化硅上的石墨烯开始，测量在栅极电压Vg = 15 V（狄拉克点）处出现的最小电导率（σmin）。发现更积极的处理（O2等离子体和UV臭氧处理）进一步将狄拉克点的栅极电压增加到高达65 V，对应于石墨烯中显示的p掺杂水平的显著增加。提出了描述施加到经处理的衬底/石墨烯表面的水滴的接触角（θ）与来自表面电荷密度的有效栅极电压之间的测量关系的电润湿模型，以描述Vg在σmin处的偏置，并且发现该电润湿模型用校正因子的乘积拟合测量，允许使用接触角测量有效地非破坏性地近似衬底添加的电荷载流子密度。
Correlations between the level of p-doping exhibited in large area chemical vapour deposition (CVD) graphene field effect transistor structures (gFETs) and residual charges created by a variety of surface treatments to the silicon dioxide (SiO2) substrates prior to CVD graphene transfer are measured. Beginning with graphene on untreated thermal oxidised silicon, a minimum conductivity (σmin) occurring at gate voltage Vg = 15 V (Dirac Point) is measured. It was found that more aggressive treatments (O2 plasma and UV Ozone treatments) further increase the gate voltage of the Dirac point up to 65 V, corresponding to a significant increase of the level of p-doping displayed in the graphene. An electrowetting model describing the measured relationship between the contact angle (θ) of a water droplet applied to the treated substrate/graphene surface and an effective gate voltage from a surface charge density is proposed to describe biasing of Vg at σmin and was found to fit the measurements with multiplication of a correction factor, allowing effective non-destructive approximation of substrate added charge carrier density using contact angle measurements.