Abstract A unique extra photoresponse of graphene field-effect transistor to the first laser pulse after a switch of back-gate voltage (VBG) is reported and explored here. It is referred as fresh-bias photoresponse (FBPR). FBPR suggests a unique prompt charge transfer process triggered by laser illumination with the help of the VBG and the transferred charge holds as far as the VBG holds unchanged. The responsible charge transfer process is proposed between ester oxygen and carbonyl carbon atoms in the ester side chains of poly(methyl methacrylate) (PMMA) molecule. The proposed mechanism explains perfectly all of the features of FBPR. The charge transfer process generates the inter-molecular dipole moment of PMMA. Such dipole moment generation is much fast than that introduced by a photo-triggered isomerization reaction of photochromic molecule, which have been used in graphene based photodetectors. This mechanism is further confirmed by the test result of a control device with mechanically exfoliated graphene channel and a control device fabricated on hexagonal boron nitride substrate. The mechanism behind FBPR may provide a new way of developing phototransistors, photodetectors or photoelectronic memory devices in the future.

中文翻译：

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石墨烯场效应晶体管的新鲜偏置光响应：电可调快速偶极矩生成

摘要 这里报道并探索了石墨烯场效应晶体管在背栅电压 (VBG) 切换后对第一个激光脉冲的独特额外光响应。它被称为新鲜偏置光响应（FBPR）。FBPR 提出了一种独特的快速电荷转移过程，由激光照射在 VBG 的帮助下触发，并且转移的电荷在 VBG 保持不变的情况下保持不变。在聚（甲基丙烯酸甲酯）（PMMA）分子的酯侧链中的酯氧和羰基碳原子之间提出了负责任的电荷转移过程。所提出的机制完美地解释了 FBPR 的所有特征。电荷转移过程产生了 PMMA 的分子间偶极矩。这种偶极矩的产生比由光致变色分子的光触发异构化反应引入的要快得多，已用于基于石墨烯的光电探测器。具有机械剥离石墨烯通道的控制装置和在六方氮化硼衬底上制造的控制装置的测试结果进一步证实了这种机制。FBPR背后的机制可能为未来开发光电晶体管、光电探测器或光电存储器件提供新的途径。