Reconfigurable Field-Effect-Transistors

可重构场效应晶体管

• 批准号: 397662129
• 负责人: Professor Dr. Joachim Knoch
• 金额: --
• 依托单位: Institut für Halbleitertechnik (IHT)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/397662129?language=en
• 关键词: Reconfigurable; Field; Effect; Transistors

During the last decades, a performance increase and thus increased functionality of highly integrated circuits (ICs) has been achieved by increasing the number of transistors of decreasing size onto the same chip area. The scalability of transistors, however, will soon come to an end. Therefore, an attractive alternative approach to further increase the functionality of ICs is to add functionality to the devices themselves. This can primarily be achieved with so-called reconfigurable contacts that allow changing the devices to work as a-type, p-type as well as band-to-band tunnel field-effect transistor (TFET) dynamically.Field effect transistors (FETs) with reconfigurable contacts consist of at least two gate electrodes, namely one that is the actual gate and the other gate electrode (the polarity gate) that allows to reconfigure the transistor. Based on such multiple-gate device architectures, a number of reconfigurable devices based on nanotubes, nanowires and two-dimensional materials have been demonstrated. In particular, switching between the operation as a conventional transistor and a TFET is very attractive since this would enable circuits that can operate either optimized to highest performance (conventional FET operation) or to lowest power consumption (TFET operation). The major drawback of all current reconfigurable FETs is the fact that the polarity gate does not change the work function of the contact metal and as a result, a Fermi level line-up at mid-gap is necessary in order to obtain similar injection of electrons and holes. Hence, carriers are always injected through a substantial Schottky-barrier which yields strongly deteriorated device characteristics. Within the present project, reconfigurable contacts with an injection probability similar to ohmic contacts for electrons and holes are realized. Furthermore, the contacts are made in a way that enables unipolar device operation which is important for proper TFET functionality. To this end, a gated sandwich consisting of a silicon channel layer, ultrathin SiNx and graphene will be employed. The graphene will be used as a metallic source electrode. While graphene-silicon diode/contact structures have been studied in literature the important addition here is the ultrathin SiNx layer in-between the graphene and the silicon. This layer is decisive in order to obtain a very low density of gap-states in the silicon which is necessary for unipolar device operation and, more importantly, for TFET operation with low off-state leakage. The low density of states in graphene around the Dirac point further decreases the density of silicon gap-states and, in addition, enables sufficient gating of the silicon through the graphene/ultrathin SiNx stack so that the conduction/valence bands can be shifted with an appropriate gate voltage. As a result, the current approach provides truly reconfigurable FETs that can operate as n-type, p-type and tunnel field-effect transistors.

在过去的几十年中，通过增加减小大小的晶体管数量到同一芯片区域的晶体管数量来实现高度集成电路（IC）的功能的提高，从而增加了高度集成电路（ICS）的功能。但是，晶体管的可伸缩性很快就会结束。因此，一种进一步提高IC功能的有吸引力的替代方法是为设备本身添加功能。这主要可以通过所谓的可重构触点来实现，该触点允许更改设备作为A型，p型以及带对波段的隧道隧道场效果晶体管（TFET）动态。对于可重构触点，至少由两个栅极电极组成，即一个是实际栅极和另一个栅极电极（极性门），允许重新配置晶体管。已经证明了基于此类多门设备架构，已经证明了许多基于纳米管，纳米线和二维材料的可重构设备。特别是，作为传统晶体管和TFET操作之间的切换非常有吸引力，因为这将使可以运行可以优化为最高性能（常规FET操作）或最低功耗（TFET操作）的电路。所有当前可重构FET的主要缺点是，极性门不会改变接触金属的工作函数，因此，需要在中间空隙处进行FERMI级别的阵容，以获得类似的电子注入和孔。因此，始终通过大量的肖特基棒向载体注入，该级驻式雪橇式轰炸机会产生强烈恶化的设备特性。在本项目中，实现了与电子和孔相似的注入概率的可重构接触。此外，触点是通过实现单极设备操作的方式进行的，这对于适当的TFET功能很重要。为此，将采用由硅通道层组成的封闭三明治，超薄Sinx和石墨烯。石墨烯将用作金属源电极。尽管在文献中已经研究了石墨烯 - 硅二极管/接触结构，但这里的重要补充是石墨烯和硅之间的超薄sinx层。该层是决定性的，以便获得硅中的间隙状态非常低的密度，这对于单极器件操作是必不可少的，更重要的是，对于低稳态泄漏的TFET操作。狄拉克点周围石墨烯中的低密度进一步降低了硅间隙状态的密度，此外，还可以通过石墨烯/超薄SINX堆栈对硅的足够门控，以便可以使用传导/价带来移动传导/价带适当的门电压。结果，当前的方法提供了真正可作为N型，P型和隧道场效应晶体管运行的可重构FET。