Nathawat Jubin, Zhao Miao, Kwan Chun-Pui, Yin Shenchu, Arabchigavkani Nargess, Randle Michael, Ramamoorthy Harihara, He Guanchen, Somphonsane Ratchanok, Matsumoto Naoki, Sakanashi Kohei, Kida Michio, Aoki Nobuyuki, Jin Zhi, Kim Yunseob, Kim Gil-Ho, Watanabe Kenji, Taniguchi Takashi, Bird Jonathan P
Department of Electrical Engineering and Department of Physics, University at Buffalo, the State University of New York, Buffalo, New York 14260, United States.
High-Frequency High-Voltage Device and Integrated Circuits Center, Institute of Microelectronics of Chinese Academy of Sciences, 3 Beitucheng West Road, Chaoyang District, Beijing 100029, PR China.
ACS Omega. 2019 Feb 22;4(2):4082-4090. doi: 10.1021/acsomega.8b03259. eCollection 2019 Feb 28.
We use transient electrical measurements to investigate the details of self-heating and charge trapping in graphene transistors encapsulated in hexagonal boron nitride (h-BN) and operated under strongly nonequilibrium conditions. Relative to more standard devices fabricated on SiO substrates, encapsulation is shown to lead to an enhanced immunity to charge trapping, the influence of which is only apparent under the combined influence of strong gate and drain electric fields. Although the precise source of the trapping remains to be determined, one possibility is that the strong gate field may lower the barriers associated with native defects in the h-BN, allowing them to mediate the capture of energetic carriers from the graphene channel. Self-heating in these devices is identified through the observation of time-dependent variations of the current in graphene and is found to be described by a time constant consistent with expectations for nonequilibrium phonon conduction into the dielectric layers of the device. Overall, our results suggest that h-BN-encapsulated graphene devices provide an excellent system for implementations in which operation under strongly nonequilibrium conditions is desired.
我们使用瞬态电学测量方法来研究封装在六方氮化硼（h-BN）中并在强非平衡条件下工作的石墨烯晶体管中的自热和电荷俘获细节。相对于在SiO衬底上制造的更标准的器件，封装显示出对电荷俘获的免疫力增强，而电荷俘获的影响仅在强栅极和漏极电场的共同影响下才明显。尽管俘获的确切来源仍有待确定，但一种可能性是强栅极场可能会降低与h-BN中固有缺陷相关的势垒，使它们能够介导从石墨烯通道中捕获高能载流子。通过观察石墨烯中电流随时间的变化来识别这些器件中的自热现象，发现其可以用一个与非平衡声子传导到器件介电层的预期相符的时间常数来描述。总体而言，我们的结果表明，h-BN封装的石墨烯器件为需要在强非平衡条件下运行的应用提供了一个出色的系统。
