Si CMOS extension and Ge technology perspectives forecast through metal-oxide-semiconductor junctionless field-effect transistor

Applications of Si have been increasingly exploited and extended to More-Moore, More-than- Moore, and beyond-CMOS approaches. Ge is regarded as one of the supplements for Si owing to its higher carrier mobilities and peculiar band structure, facilitating both advanced and optical applications. As an emerging metal-oxide device, the junctionless field-effect transistor (JLFET) has drawn considerable attention because of its simple process, less performance fluctuation, and stronger immunity against short-channel effects due to the absence of anisotype junctions. In this study, we investigated lateral field scalability, which is equivalent to channel-length scaling, in Si and Ge JLFETs. Through this, we can determine the usability of Si CMOS and hypothesize its replacement by Ge. For simulations with high accuracy, we performed rigorous modeling for μ_n and μ_p of Ge, which has seldom been reported. Although Ge has much higher μ_n and μ_p than Si, its saturation velocity (v_sat) is a more determining factor for maximum I_on. Thus, there is still room for pushing More-Moore technology because Si and Ge have a slight difference in v_sat. We compared both p- and n-type JLFETs in terms of I_on, I_off, I_on/I_off, and swing with the same channel doping and channel length/thickness. I_on/I_off is inherently low for Ge but is invariant with V_DS. It is estimated that More-Moore approach can be further driven if Si is mounted on a JLFET until Ge has a strong possibility to replace Si for both p- and n-type devices for ultra-low-power applications.