Interfacial perfection for pushing InGaAs and Ge MOS device limits (invited)

The in-situ deposited high κ gate dielectrics, Ga
2
O
3
(Gd
2
O
3
)[GGO], Y
2
O
3
, HfO
2
, and Al
2
O
3
, on freshly molecular beam epitaxy (MBE) grown In
0.53
Ga
0.47
As (InGaAs) have perfected the interfacial electronic (chemical) characteristics, thus achieving low interfacial trap densities (D
it
) and high-temperature thermal stability. These enable fabrication of self-aligned inversion- channel InGaAs metal-oxide-semiconductor field-effect- transistors (MOSFETs) using a CMOS compatible process, giving very high drain currents (I
d
) of 1.05-1.8 mA/μm and transconductances (G
m
) of 0.714-0.98 mS/μm in 1μm gate length (L
g
) devices; Synchrotron radiation photoemission spectroscopy (SRPES) reveals no AsO
x
residue at the in-situ atomic layer deposited (ALD)-Al
2
O
3
/InGaAs interface, while some AsO
x
remains using the ex-situ method. The in-situ 1μm L
g
GGO/Ge pMOSFETs have given I
d
of 0.496 mA/μm, G
m
of 0.178 mS/ μm, and effective hole mobility of 389 cm
²
/V s. On the formation of Schottky barrier height (SBH) of Ag/GaAs, SRPES core-level data show that Ag adatoms effectively passivate the surface As-As dimers in the initial Ag deposition. A SBH of 0.38 eV is secured at Ag 0.25 Å thick prior to the formation of an Ag metal. The final SBH is similar to the measured value at the initial Ag deposition.