Fermi level unpinning achievement and transport modification in Hf1-Yb O /Al2O3/GaSb laminated stacks by doping engineering

Abstract

Fermi level pinning and interface instability have hindered the achievement of field-effect-transistors (FETs) with high performance. Interface passivation and doping engineering technology have become the main driving force to solve the issue. Herein, interface chemistry and transport characteristics determination of Hf1-xYbxOy/Al2O3/GaSb gate stacks have been achieved by passivation and doping process. X-ray photoelectron spectroscopy characterization and electrical measurements have demonstrated the existence of less intrinsic oxides and elemental Sb at Hf1-xYbxOy/Al2O3/GaSb interface with optimized doping content, as well as the minimum leakage current density of 2.23 × 10–5 A cm-2. The energy distribution of interface state based on conductance method has confirmed the achievement of the lowest interface state density of 1.98×1013 eV-1 cm-2, resulting in Fermi level unpinning. Carrier transport mechanisms of Hf1-xYbxOy/Al2O3/GaSb MOS capacitors as a function of temperature have been investigated systematically and some important electrical parameters have been extracted. Comprehensive analyses show that sputtering-derived Hf1-xYbxOy/Al2O3/GaSb (x = 0.32) gate stack has potential application in future GaSb-based metal-oxide-semiconductor field effect transistor (MOSFET) devices.