High k/III-V structures: Interfaces, oxides quality and down scaling
In this paper, we present our studies on high k/InGaAs and high k/InSb structures, focusing on the interfaces, oxides qualities as well as down scaling the gate oxide. We indicate the free movement of Fermi level in both kinds of n- and p-InGaAs MOSCAPs. The effect of gases plasma treatments in the improvement of gate oxides as well as high k/InGaAs interface quality is also discussed. For high k/InSb structure, the effect of post deposition annealing temperatures on electrical properties of this structure is presented. Finally, we present our efforts on down scaling the equivalent oxide thickness of these structures into sub-nm size.
Interface study of high-k/InAs/n-GaSb MOSCAP structures
Interface properties of Al 2 O 3 , HfO 2 and TiO 2 of 5 nm on GaSb substrate passivated with 2nm InAs were studied and compared. The interface properties of Al 2 O 3 /InAs/n-GaSb and HfO 2 /InAs/n-GaSb structures are reported, but no interface characterization of TiO 2 /InAs/n-GaSb has been done till today. In this paper, the capacitance voltage (C-V) characteristic of Al 2 O 3 /InAs/n-GaSb, HfO 2 /InAs/n-GaSb and TiO 2 /InAs/n-GaSb MOSCAP structures were simulated using TCAD tool at 300K. Thereafter, interface trap density (D it ), threshold voltage (V th ), flatband voltage (V fb ) and surface potential (Φ s ) were obtained by C-V and compared. The D it values for Al 2 O 3 /InAs/n-GaSb, HfO 2 /InAs/n-GaSb and TiO 2 /InAs/n-GaSb MOSCAP structures were determined by Termann method and found to be 3.38×1012 cm−2eV−1, 1.15×1012 cm−2eV−1 and 9.11×1011 cm−2eV−1 respectively. It is interesting to note that the D it value reduces by 65% in case of HfO 2 /InAs/n-GaSb, whereas by 75% in case of TiO 2 /InAs/n-GaSb structure compared to Al 2 O 3 /InAs/n-GaSb structure. Furthermore, the TiO 2 /InAs/n-GaSb structure has insignificant threshold voltage variation and much less flatband voltage variation for different oxide thicknesses ranging from 5nm to 10nm.
The significance of core-level electron binding energies on the proper analysis of InGaAs interfacial bonding
The detection and removal of interfacial oxides on InGaAs semiconductors is of critical importance for their implementation as high-mobility channels for improved complementary metal oxide semiconductor device performance. X-ray photoelectron spectroscopy is a powerful tool to determine the chemical bonding at these interfaces. To correctly analyze these spectra, one must consider the binding energies and escape depths of the core-level electrons being detected, as monolayer level interfacial oxides (As–O and Ga–O) are detectable only in certain surface sensitive spectral regions. Also, inherent asymmetries associated with the In spectra must be taken into account for analysis of In-oxide bonding.