Channel passivation of SiGe and InGaAs requires removal of dangling bonds and formation of a thermally stable interface.  On InGaAs, one solution is the deposition by self-limiting CVD or ALD of a few monolayer of silicon, silicon oxide, or silicon nitride.  To form an Si-OH terminated In_0.53Ga_0.47As(001) surface, two monolayers of Si were deposited at 350°C with self-limiting CVD using Si₂Cl₆  dosing following by dosing anhydrous HOOH(g).  Scanning tunneling microcopy (STM) shows and ordered surface is form while scanning tunneling spectroscopy (STS) shows the surface Fermi level position moves towards midgap due to a surface dipole formation from –OH groups and oxygen bonding to the surface.  TMA was dosed at 250°C onto the Si-OH terminated InGaAs(001), and XPS shows the emergence of the Al 2p and C 1s peaks indicative of TMA surface nucleation.  The TMA shifts the InGaAs Fermi level back towards the conduction band, consistent with unpinning.   MOSCAPs were fabricated to further demonstrate Fermi level unpinning using the Si-OH termination of InGaAs.

While this same Si deposition process could be employed on SiGe, a  simple annealing process can be employed to form a silicon terminated SiGe surface. A saturation dose of H₂O₂(g) at 25^oC chemisorbs to on Si_0.5Ge_0.5(110) and Si_0.47Ge_0.53(001)  surfaces leaving the Fermi level on the surface unpinned, and the surface is functionalized with mainly Si-OH, Ge-OH and Si-O-Ge bond.  After a subsequent TMA dose at 25^oC and annealing at 300^oC, XPS and STM verify that a thermally stable and well-ordered monolayer of Al₂O₃ is formed on SiGe(110) and (001) surfaces with only Al-O-Si bonds and no detectable Ge-O-Si bonds. The H₂O₂(g) functionalization provides 3 times higher  O sites on the surface and 3 times higher TMA nucleation density than H₂O(g) at 25°C and 120°C. 

A variety of strongly bound passivating atoms can induce formation of a nearly pure Si interfacial layer between high-k dielectrics and SiGe. This annealing procedure was employed to form MOSCAP on SiGe(001) using Al₂O₃ and HfO₂ gate oxides after either (NH₄)₂S or NH₃ plasma passivation.  For NH₃ plasma passivation, angle-resolved XPS showed that the annealing allows formation of nearly Ge-free SiON layer.  For higher Ge concentrations, the annealing process is unlikely to form a nearly Ge-free SiON layer so a novel plasma-free chemistry has been develop to deposit SiON using  ALD with N₂H₄(g) as a precursor.