\textit{In-situ} photoemission analyses of ALD-oxide/In$_{x}$Ga$_{1-x}$As (001) interfaces

High-$\kappa $ dielectrics on high carrier mobility channels, such as In$_{x}$Ga$_{1-x}$As, are now being considered for CMOS technology beyond 15 nm node. The initial bonding of high-$\kappa $/InGaAs determines the value and the distribution of interfacial density of states (D$_{it})$ within the In$_{x}$Ga$_{1-x}$As band gap, key to the device performance. In this work, atomic layer deposited (ALD) HfO$_{2}$ and Al$_{2}$O$_{3}$ on MBE-grown In$_{x}$Ga$_{1-x}$As (001) have been \textit{in-situ} and \textit{ex-situ} carried out to investigate the initial stage of interfacial reactions by high resolution photoemission spectroscopy using synchrotron radiation and monochromatic Al Ka x-ray sources. Comparing the results with the corresponding electrical measurements (C-V and G-V at various temperatures), Fermi level unpinning in the oxide/In$_{x}$Ga$_{1-x}$As hetero-structure may be attributed to the exclusion of the As-As and the As-O bonding during the initial interfacial formation.