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.
High-indium-content InGaAs metal-oxide-semiconductor capacitor with amorphous LaAlO3 gate dielectric
The structure and electrical properties of LaAlO3∕n-In0.53Ga0.47As metal-oxide-semiconductor capacitors deposited by molecular-beam epitaxy were investigated. Transmission electron microscopy revealed a sharp interface between the dielectric and InGaAs. Postdeposition annealing at 440–500°C significantly reduced the capacitive equivalent thickness and frequency dispersion. A hysteresis of 15mV–0.1V, a dielectric permittivity of 17±1, and a dielectric strength of ∼4.3MV∕cm were measured. Additionally, a high loss in the parallel conductance and gate-bias independence in the inversion region was observed, implying the fast generation rate of minority carriers in In0.53Ga0.47As.