Electron mobility enhancement in strained-germanium n-channel metal-oxide-semiconductor field-effect transistors

Abstract

The dependence of electron mobility on strain, channel direction, and substrate orientation is theoretically studied for the germanium n-channel metal-oxide-semiconductor field-effect transistors. For the unstrained channel, (111) substrate can provide the highest mobility among the three orientations, mainly due to its largest quantization mass and smallest conductivity mass in L valley. The tensile strain parallel to the [(1) over bar 10] channel direction on (111) substrate gives 4.1 times mobility of Si at 1 MV/cm, and the mobility enhancement starts to saturate for the strain larger than 0.5%. The compressive strain of similar to 1.5% transverse to [(1) over bar 10] on (111) substrate yields 2.9 times mobility enhancement at 1 MV/cm. (c) 2007 American Institute of Physics

Structural and band alignment properties of Al2O3 on epitaxial Ge grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy

“…16 The l n of Ge with (111) orientation is 1.8Â higher than that of (100) and (110) orientations. 18 Moreover, the reported l h of (110) Ge channel, orientation along the h110i direction, exhibited 2.3Â higher l h compared with the (100) Ge. 19 Thus, Ge CMOS with high-j gate dielectrics is very attractive as one of the post-Si device options with higherperformance and low-power operation.…”

Growth of Ge Homoepitaxial Films by Metal-Organic Chemical Vapor Deposition Using t-C4H9GeH3

“…[20][21][22][23] Furthermore, it is extremely safe without any explosive or pyrophoric natures, and never react with H 2 O. Thus, our selected precursor has much safer than other metal-hydride CVD precursors such as GeH 4 and Ge 2 H 6 . [24][25][26][27][28] We believe the safe precursor is appropriate for the scientific experiment and even for the commercial mass production.…”

“…1 Thus, it is considered to be one of the promising post scaling materials. [2][3][4][5] Moreover, we believe that Ge homoepitaxial technique is also essential to realize Ge 1-x Sn x heteroepitaxial growth. A simultaneous supply with Sn precursor such as tetraethyl tin [(C 2 H 5 ) 4 Sn] enables to grow the Ge 1-x Sn x heteroepitaxial films.…”

“…[2][3][4][5] Moreover, we believe that Ge homoepitaxial technique is also essential to realize Ge 1-x Sn x heteroepitaxial growth. A simultaneous supply with Sn precursor such as tetraethyl tin [(C 2 H 5 ) 4 Sn] enables to grow the Ge 1-x Sn x heteroepitaxial films. 6,7 Ge 1-x Sn x can be also used as a channel material and a stressor for Ge MOSFETs.…”

Tailoring strain in microelectronic devices

“…A few percent strain can increase the electron mobility µ in silicon by a factor of three [57][58][59], while at the same time the subthreshold current may . .…”