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High mobility NMOSFET structure with high-/spl kappa/ dielectric


Abstract:

High-/spl kappa/ NMOSFET structures designed for enhancement mode operation have been fabricated with mobilities exceeding 6000 cm/sup 2//Vs. The NMOSFET structures which...Show More

Abstract:

High-/spl kappa/ NMOSFET structures designed for enhancement mode operation have been fabricated with mobilities exceeding 6000 cm/sup 2//Vs. The NMOSFET structures which have been grown by molecular beam epitaxy on 3-in semi-insulating GaAs substrate comprise a 10 nm strained InGaAs channel layer and a high-/spl kappa/ dielectric layer (/spl kappa//spl cong/20). Electron mobilities of >6000 and 3822 cm/sup 2//Vs have been measured for sheet carrier concentrations n/sub s/ of 2-3/spl times/10/sup 12/ and /spl cong/5.85/spl times/10/sup 12/ cm/sup -2/, respectively. Sheet resistivities as low as 280 /spl Omega//sq. have been obtained.
Published in: IEEE Electron Device Letters ( Volume: 26, Issue: 10, October 2005)
Page(s): 713 - 715
Date of Publication: 31 October 2005

ISSN Information:


I. Introduction

Charge carrier mobility continues to be a key parameter for MOSFET performance beyond the 90-nm technology node of the International Technology Roadmap for Semiconductors (ITRS). Typical electron mobilities in Si MOSFETs with gate dielectric are around 500–600 for inversion charge densities [1]. Mobility enhancement factors between 1.6 and 2 were measured using layers of strained SiGe or Ge, respectively [2] [3] [4]. However, the use of high- dielectrics such as reduces mobility; typical peak electron mobilities for Si bulk MOSFETs with gate dielectric are 200 [1], [5]. A future alternative to Si bulk and Si-based strained layer MOSFETs are layer structures based on III-V compound semiconductors [6], [7]. For the first time, the latest edition of the ITRS roadmap includes serious references to compound semiconductor based transistors as a “nonclassical” CMOS solution to continue long term scaling according to Moore's Law. Further, a number of RF applications, in particular in the wireless and mobile product space, will benefit from performance enhancements potentially provided by III-V MOSFETs. NMOSFET layer structure. The -dopings are indicated by dashed lines. This letter reports on electron mobilities as high as 6,155 in GaAs enhancement mode NMOSFET structures employing a high- dielectric () and a strained InGaAs channel layer with a thickness of 10 nm.

References

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