Fermi level unpinning of GaSb(100) using Plasma Enhanced ALD Al2O3 dielectric

Antimonide based compound semiconductors have gained considerable interest in recent years due to their superior electron and hole transport properties [1–3]. Among the various high mobility material systems (Fig. 1), arsenic-antimonide based MOS-HEMTs have great potential to enable complementary logic operation at low supply voltage. Integrating a high quality dielectric is key to demonstrating a scalable arsenic-antimonide MOS-HEMT architecture for 15 nm logic technology node and beyond. It is hypothesized that an ultra-thin GaSb surface layer is more favorable toward high-к integration than In 0.2 Al 0.8 Sb barrier as it avoids Al at the interface and the associated surface oxidation. Here, we study the effects of various surface passivation approaches on the capacitance-voltage characteristics (C-V) and the surface chemistry of n-type and p-type GaSb(100) MOS capacitors made with ALD and Plasma Enhanced ALD (PEALD) Al 2 O 3 dielectric. We demonstrate for the first time, unpinned Fermi level in GaSb MOS system with high-к PEALD Al 2 O 3 dielectric using admittance spectroscopy and XPS analysis.