Balanced Performance Improvement and Low-Frequency Noise of TMA-Passivated GaSb MOS Capacitors Using Bilayered HfO2/Al2O3 Gate Dielectrics

The exploitation of high-performance GaSb metal–oxide–semiconductor (MOS) devices is severely limited by unstable interface and Fermi-level pinning effect. Herein, bilayered dielectric engineering is proposed to improve and balance the interface and electrical properties of GaSb MOS capacitors. The impacts of stacking sequence and sublayer thickness ratio of HfO2 and Al2O3 gate dielectrics on the interface chemistry and transport modification of trimethylaluminum (TMA)-passivated GaSb MOS capacitors are systematically explored. The GaSb MOS capacitors configured with HfO2/Al2O3 stacking sequence and 7-/3-nm thickness ratio passivate trap charges effectively and demonstrate the balanced performances with an oxide charge density of
$- 3.95\times 10^{{10}}$
cm−2, an interface state density of
$10.19\times 10^{{12}}$
cm−2, a leakage current density of
$8.49\times 10^{-{6}}$
A/cm2, a dielectric constant value of 20, as well as unpinned Fermi level. Besides, the transformation of leakage current conduction mechanisms (CCMs) with electric field and temperature is comprehensively expounded. What is more, low-frequency noise (LFN) is discussed for the first time in GaSb MOS devices and provides convincing evidence that GaSb MOS capacitor with laminated 7-nm HfO2/3-nm Al2O3 has less traps, which makes it a promising gate dielectric for future GaSb high-mobility transistor devices.