In this study preparation and properties of InGaAs/GaAs MOS structures with double-layer insulator consisting of oxygen-plasma oxide covered by Al2O3 are presented. Structures with 75 s and 150 s oxidation time were used. Static measurements yielded saturation drain current of ~250 mA/mm at VG = 1 V. Capacitance measurements showed improved performance in depletion region comparing with structures without double-layer insulator. Trapping effects were investigated by conductance vs frequency measurements. Trap state density in order of 1011 cm-2eV-1 with its continuous decrease with increased trap energy was evaluated. Carrier mobility evaluation showed peak values of 3950 cm2V-1s-1s for 75 s and 4570 cm2V-1s-1s for 150 s oxidation times with the sheet charge density ~2 × 1012 cm-2. All these demonstrate high capability of used preparation procedure of GaAs-based MOS devices with oxidized GaAs surface covered by Al2O3 insulator.
Gucmann, F., Gregušová, D., Stoklas, R., Dérer, J., Kúdela, R., Fröhlich, K., and Kordoš, P.: InGaAs/GaAs metal-oxide-semiconductor heterostructure field-effect transistors with oxygen-plasma oxide and Al2O3double-layer insulator. Applied Phys. Lett. 105 (2014) 183504.