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硅纳米线场效应晶体管在射频应用上取得新进展
发表时间:2013-03-22 阅读次数:2581次

        由于摩尔定律进一步的延续,尺寸化缩小带领着当前半导体产业的持续发展。纳米结构由于其高密度集成,吸引了广泛的研究注意。更重要的,纳米结构器件提供了超越传统方法的缩小思路。当我们将目光注意到他们本身的性质可以带来的电路应用时,可以发现新的思路。近年来,无线通讯的发展要求人们尽可能的利用频谱资源,然后过度集中会导致类似于交通堵塞一样的后果。为了降低互调制和谐振扭曲,需要复杂的线性系统来解决。然而,如果在器件级别实现线性系统,能够大大降低电路的复杂性。

        美国普度大学(Purdue University)的Joerg Appenzeler研究小组在硅纳米线场效应晶体管的射频电路应用上取得新进展,相关成果发表在Nano Letters。他们利用一维输运(1-D transport),器件工作在量子电容限制(quantum capacitance limit)和弹道输运(ballistic transport)条件下,在器件级别实现了高度的线性跨导。通过这项研究,在低电压和低维度器件级别下实现了线性跨导,这为射频电路应用提供新的思路。相关的结构发表在Nano letters上。不同于传统的金属氧化物半导体场效应晶体管(大部分栅电压降落在栅氧化物上),在量子电容限制条件下操作的器件意味着Cox远远大于量子电容CQ,降落在栅氧上的电容可以被忽略不计。一维输运下,态密度和群速度之积被相互抵消;沟道的输运速度主要由能量色散E(K)决定,而且透射概率一样大。这样,在饱和区域下Id-Vgs满足如下关系: .研究人员制备了环栅(GAA)n-MOS硅纳米线晶体管,沟道半径约为6 nm从而保证1-D输运。沟道长度约为250 nm,满足低温下的近似弹道输运条件。

Figure 1 硅纳米线场效应晶体管器件结构图

 

Figure 2 1-D输运

 

Figure 3 1-D输运,量子电容限制和弹道输运下的转移特性曲线

        

Figure 4 转移特性曲线,跨导在一定的范围内为常数

 

原文英文摘要

        Nanostructures have attracted a great deal of attention because of their potential usefulness for high density applications. More importantly, they offer excellent avenues for improved scaling beyond conventional approaches. Less attention has been paid to their intrinsic potential for distinct circuit applications. Here we discuss how a combination of 1-D transport, operation in the quantum capacitance limit, and ballistic transport can be utilized for certain RF applications. In particular this work explores how the above transport properties can provide a high degree of transconductance linearity at the device level. The article also discusses how device characteristics can be interpreted and analyzed in terms of device linearity if the above conditions are not ideally fulfilled. Using aggressively scaled silicon nanowire field-effect transistors as an example device in this work provides new insights toward the proper choice of channel material to improve linearity through the above-mentioned transport conditions. According to this study, a high degree of linearity occurs feasible while operating at low supply voltages making low-dimensional systems, and here in particular nanowires, an interesting candidate for portable RF applications.

 

原位链接地址

http://pubs.acs.org/doi/pdf/10.1021/nl3047078

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