Hydrogen plasma enhanced oxide removal on GaSb planar and nanowire surfaces

Due to its high hole-mobility, GaSb is a highly promising candidate for high-speed p-channels in electronic devices. However, GaSb exhibits a comparably thick native oxide causing detrimental interface defects, which has been proven difficult to remove. Here we present full oxide removal from GaSb surfaces using effective hydrogen plasma cleaning, studied in-situ by synchrotron-based X-ray photoelectron spectroscopy under ultra-high vacuum (UHV). GaSb nanowires turn out to be cleaned faster and more efficiently than planar substrates. Since the UHV conditions are not scalable for industrial sample processing, H-plasma cleaning is furthermore used as pre-treatment prior to atomic layer deposition (ALD) of a protective high-k layer to demonstrate the use of the cleaning step in a more realistic fabrication situation. We observe a cleaning effect of the H-plasma even in the ALD environment, but we also find residual Ga-and Sb-oxides at the GaSb-high-k interface, which we attribute to re-oxidation of the cleaned surface. Our results indicate that an improved control of the ALD reactor vacuum environment could realize oxide-and defect-free interfaces in GaSb-based electronics.

Automated summary

GaSb, with its high hole-mobility, is a promising material for high-speed p-channels in electronic devices. However, the thick native oxide of GaSb causes detrimental interface defects that are difficult to remove. In this study, we successfully remove the oxide from GaSb surfaces using hydrogen plasma cleaning, and find that this method is more efficient for cleaning GaSb nanowires compared to planar substrates. Furthermore, the hydrogen plasma cleaning is used as a pre-treatment in a realistic fabrication situation, showing its potential for improving the control of oxide-and defect-free interfaces in GaSb-based electronics.