Perfecting high-κ/Ge and /InGaAs interfaces – push for ultimate CMOS and emerging cryogenic electronic devices

This paper reviews our work on perfecting high-κ/epi-Si/Ge and high-κ/InGaAs interfaces using in-situ HfO
2
and Y
2
O
3
, respectively. The heterostructures were grown in our designed ultra-high vacuum (UHV) deposition/ analysis system. The perspective of the work on the related technologies is given. We have employed high-resolution synchrotron radiation photoemission and X-ray diffraction to study the electronic structures and the crystallography of the in-situ prepared gate stacks. Using the in-situ HfO
2
on epi-Si/Ge, low interface state density (D
it
) values of (2-4) × 10
¹¹
eV
^-1
cm
^-2
and small charge trapping with a high acceleration factor (γ) of 11 were achieved simultaneously; these are comparable to the state-of-the-art results in the Ge MOS devices using GeO
x
-based gate stack and thin Si cap via chemical vapor deposition, respectively. The in-situ Y
2
O
3
has effectively passivated InGaAs surface in attaining record-low D
it
values of (2-4) × 10
¹¹
eV
^-1
cm
^-2
and high thermal stability of 800 ℃ among the high-κ/InGaAs heterostructures. The results have enabled the attainment of record-low subthreshold slope (SS) values in planar inversion-channel InGaAs metal-oxide-semiconductor field-effect-transistors (MOSFETs). The SS values of 22 mV/dec at 77 K and a slope factor m of 1.33, the lowest among the planar InGaAs MOSFETs, were achieved, which are comparable to those obtained in the ultra-thin-body InGaAs FinFETs.