Howe Leslie, Ellepola Kalani H, Jahan Nusrat, Talbert Brady, Li James, Cooney Michael P, Vinh Nguyen Q
Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia 24061, United States.
NASA Langley Research Center, Hampton, Virginia 23681, United States.
ACS Appl Electron Mater. 2025 Jan 22;7(3):1305-1313. doi: 10.1021/acsaelm.4c02268. eCollection 2025 Feb 11.
Infrared photodetection of silicon is prevented by the bandgap energy at wavelengths longer than approximately 1100 nm (∼1.12 eV) at room temperature, while silicon is the most used in modern electronics. Of particular interest is the performance of silicon for photodetectors in the infrared region beyond the silicon bandgap. Here, we demonstrate graphene field-effect transistor photodetectors on silicon with high photoconductive gain and photodetection capability extending to the infrared region. These devices have a photoresponsivity of >10 A/W for excitation above the silicon bandgap energy and yield a value of 35 A/W for infrared detection at a wavelength of 1530 nm. The high photosensitivity of the devices originates from the photogating effect in the nanostructures and a long Urbach tail extending into the infrared region. A model to explain the mechanism of the photoconductive gain is proposed, which shows that the gain results from modulation of the surface charge region under illumination. The gain strongly depends on the excitation power, due to carrier capture processes occurring over the barriers associated with the surface charge region, in agreement with the experimental data. This model properly explains the photoresponse behavior of graphene field-effect transistors on silicon.
在室温下，硅在波长大于约1100纳米（~1.12电子伏特）时，会因带隙能量而无法进行红外光电探测，而硅却是现代电子学中使用最广泛的材料。特别令人感兴趣的是硅在硅带隙之外的红外区域用作光电探测器的性能。在此，我们展示了基于硅的石墨烯场效应晶体管光电探测器，其具有高光电导增益以及延伸至红外区域的光电探测能力。对于高于硅带隙能量的激发，这些器件的光响应度大于10 A/W，在1530纳米波长处进行红外探测时，光响应度值为35 A/W。器件的高光敏性源于纳米结构中的光门控效应以及延伸至红外区域的长乌尔巴赫尾。提出了一个解释光电导增益机制的模型，该模型表明增益源于光照下表面电荷区域的调制。由于与表面电荷区域相关的势垒上发生载流子俘获过程，增益强烈依赖于激发功率，这与实验数据相符。该模型恰当地解释了基于硅的石墨烯场效应晶体管的光响应行为。
