Han Sangmoon, Lee Seoung-Ki, Choi Ilgyu, Song Jihoon, Lee Cheul-Ro, Kim Kangmin, Ryu Mee-Yi, Jeong Kwang-Un, Kim Jin Soo
Applied Quantum Composites Research Center , Korea Institute of Science and Technology , Wanju 55324 , South Korea.
Department of Physics , Kangwon National University , Chuncheon 24341 , South Korea.
ACS Appl Mater Interfaces. 2018 Nov 7;10(44):38173-38182. doi: 10.1021/acsami.8b11229. Epub 2018 Oct 26.
In this study, we report highly efficient and flexible photosensors with GaN nanowires (NWs) horizontally embedded in a graphene sandwich structure fabricated on polyethylene terephthalate. GaN NWs and the graphene sandwich structure are used as light-absorbing media and the channel for carrier movement, respectively. To form uniform high-quality crystalline GaN NWs on Si(111) substrates, the initial nucleation behavior of the NWs was manipulated by applying the new growth technique of Ga predeposition. High-resolution transmission electron microscopic images obtained along the vertical direction of GaN NWs showed that stacking faults, typically observed in Si-based (In,Ga)As NWs, were rare. Consequently, narrow and strong optical emission was observed from the GaN NWs at wavelengths of 365.12 nm at 300 K. The photocurrent and photoresponsivity of the flexible photosensor with 802 nm long GaN NWs horizontally embedded in the graphene sandwich channel were measured as 9.17 mA and 91.70 A/W, respectively, at the light intensity of 100 mW/cm, which are much higher than those previously reported. The high optical-to-electrical conversion characteristics of our flexible photosensors are attributed to the increase in the effective interface between the light-absorbing media and the carrier channel by the horizontal distribution of the GaN NWs within the graphene sandwich structure. After 200 cyclic-bending test of the GaN NW photosensor at the strain of 3%, the photoresponsivity under strain was measured as 89.04 A/W at 100 mW/cm, corresponding to 97.1% of the photoresponsivity obtained before bending. The photosensor proposed in this study is relatively simple in device design and fabrication, and it requires no sophisticated nanostructural design to minimize the resistance to metal contacts.
在本研究中，我们报道了一种高效且灵活的光电传感器，其具有水平嵌入在聚对苯二甲酸乙二酯上制备的石墨烯三明治结构中的氮化镓纳米线（NWs）。氮化镓纳米线和石墨烯三明治结构分别用作光吸收介质和载流子移动通道。为了在硅（111）衬底上形成均匀高质量的晶体氮化镓纳米线，通过应用镓预沉积的新生长技术来控制纳米线的初始成核行为。沿氮化镓纳米线垂直方向获得的高分辨率透射电子显微镜图像表明，在硅基（铟，镓）砷纳米线中通常观察到的堆垛层错很少见。因此，在300 K时，从氮化镓纳米线在365.12 nm波长处观察到窄而强的光发射。对于水平嵌入石墨烯三明治通道中的802 nm长的氮化镓纳米线的柔性光电传感器，在100 mW/cm的光强度下，其光电流和光响应率分别测量为9.17 mA和91.70 A/W，这远高于先前报道的值。我们的柔性光电传感器的高光电转换特性归因于氮化镓纳米线在石墨烯三明治结构内的水平分布增加了光吸收介质与载流子通道之间的有效界面。在对氮化镓纳米线光电传感器进行3%应变下的200次循环弯曲测试后，在100 mW/cm下测量的应变下的光响应率为89.04 A/W，相当于弯曲前获得的光响应率的97.1%。本研究中提出的光电传感器在器件设计和制造方面相对简单，并且不需要复杂的纳米结构设计来最小化金属接触电阻。
