The controlled modification of graphene's electronic band structure poses serious challenges. In the present work, we study the effect of sp 2 cluster size variation on the electronic band gap and photoconductive properties of reduced graphene oxide (RGO). This is achieved by performing reversible functionalization of RGO with oxygen species. The reversible functionalization of RGO results in its partial transformation to graphene oxide (GO) so that the size of the sp 2 clusters within the sp 3 matrix varies, thereby affecting the π-π* band structure and photoconductive properties. The study reveals: (1) incremental creation/elimination of oxygenated surface bonds' related energy states within the π-π* band; (2) customized tuning of the sp 2/sp 3 ratio; (3) the presence/absence of oxygenated states impacts the optical transition processes both from band-to-band and oxygenated states; and (4) the incremental addition/depletion of surface states in a tunable manner directly influences the carrier transport in the photoconductive device. Experiments show a two-stage transformation of RGO electronic properties with changing oxygen functionalities: oxidation (Stage I) and decomposition or erosion (Stage II). Sp 2 cluster size variation induced bandgap change was analyzed by Raman and photoluminescence studies, indicating the possibility for photodetection in a specific band encompassing NIR to UV, depending on the sp 2/sp 3 ratio. Energy-dispersive x-ray spectroscopy and Fourier transform infrared studies confirm the surface oxygenation/de-oxygenation during plasma treatment, and XRD confirms partial transformation of RGO to GO and its amorphization at higher plasma exposure times. In addition, the photodetector performance is optimized in terms of carrier generation-recombination and carrier-lattice scattering. Thus, manipulating better photoconductive response is possible through suitable handling of the parameters involved in the plasma treatment process. This is the first study on the influence of the sp 2/sp 3 ratio-induced lattice structure evolution on photodetection.

中文翻译：

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GO的可逆合成：微分键结构转换在微调光电探测器响应中的作用

石墨烯电子能带结构的可控修饰提出了严峻的挑战。在目前的工作中，我们研究了 sp 2 簇尺寸变化对还原氧化石墨烯 (RGO) 的电子带隙和光电导性能的影响。这是通过用氧物种对 RGO 进行可逆功能化来实现的。RGO 的可逆功能化导致其部分转变为氧化石墨烯 (GO)，因此 sp 3 基质中 sp 2 簇的大小发生变化，从而影响 π-π* 能带结构和光电导性能。研究表明：(1) π-π* 带内氧化表面键相关能态的增量产生/消除；(2) 自定义调整 sp 2/sp 3 比率；(3) 氧合状态的存在/不存在影响从带到带和氧合状态的光学跃迁过程；(4) 表面态以可调方式的增量增加/减少直接影响光电导器件中的载流子传输。实验表明，随着氧官能度的变化，RGO 电子特性的两阶段转变：氧化（第一阶段）和分解或侵蚀（第二阶段）。通过拉曼和光致发光研究分析了 Sp 2 簇大小变化引起的带隙变化，表明在包含 NIR 到 UV 的特定波段中进行光电检测的可能性取决于 sp 2/sp 3 比率。能量色散 X 射线光谱和傅里叶变换红外研究证实了等离子体处理过程中的表面氧化/脱氧，XRD 证实了 RGO 向 GO 的部分转变及其在更高的等离子体暴露时间下的非晶化。此外，在载流子生成-复合和载流子-晶格散射方面优化了光电探测器的性能。因此，通过适当处理等离子体处理过程中涉及的参数，可以操纵更好的光电导响应。这是首次研究 sp 2/sp 3 比率诱导的晶格结构演化对光电探测的影响。通过适当处理等离子体处理过程中涉及的参数，可以操纵更好的光电导响应。这是首次研究 sp 2/sp 3 比率诱导的晶格结构演化对光电探测的影响。通过适当处理等离子体处理过程中涉及的参数，可以操纵更好的光电导响应。这是首次研究 sp 2/sp 3 比率诱导的晶格结构演化对光电探测的影响。