Atomic Layer Deposited Rare Earth Oxide Y₂O₃ on n-GaSb(001)
Y. H. Lin1*, K. Y. Lin1, L. B. Young1, K. H. Chen1, C. H. Fu1, W. J. Hsueh2, G. J. Brown3, T. W. Pi4, J. I. Chyi2, J. Kwo5, M. Hong1
1Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan
2Department of Electrical Engineering, National Central University, Jhongli, Taiwan
3Air Force Research Laboratory, Dayton, Ohio, USA
4National Synchrotron Radiation Research Center, Hsinchu, Taiwan
5Department of Physcis, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Yen-Hsun Lin, email:f01222018@ntu.edu.tw
Antimony-based compound semiconductors have attracted much attention for the applications of infrared detectors, high-speed low-power consumption ultimate CMOS, owing to their wide-range tunable band gap and high carrier mobility. Similar to arsenic-based III-V semiconductors, the native oxide SbOx is the main obstacle to passivate GaSb surface. The formation of low-oxidation state or elemental Sb during conventional ex-situ process is inevitable, leading to Fermi-level pinning and poor interfacial property. Suitable high-κ oxides with productive growth method to passivate GaSb is strongly in demand.

Atomic layer deposition (ALD) is a proven production technique since the 45-nm node Si CMOS. With its great conformal coverage and atomic layer-by-layer growth nature, ALD is widely employed in the present research and manufacture for many fields, ranging from electronic to energy applications. However, compared with Molecular Beam Epitaxy (MBE)-grown high-κ oxides, ALD high-κ oxides usually gives inferior interfacial properties at oxide/GaSb interface. Researchers have been suffered from this issue over a decade. Here, we have developed a novel method to improve the ALD-oxide layer quality by annealing the hetero-structure in ultra-high-vacuum (UHV) environment. Because MBE-Y2O3 has been demonstrated to passivate GaSb(001) with excellent device performance, ALD-Y2O3/n-GaSb(001) was chosen in this study. X-ray photoelectron spectroscopy (XPS) was taken to investigate the interface bonding evolution during ALD-Y2O3 deposition and UHV annealing. Metal-Oxide-Semiconductor capacitors (MOSCAPs) were fabricated to analyze the interfacial electrical properties. The improved interface of UHV-annealed ALD-Y2O3/n-GaSb(001) has attained high quality oxide/semiconductor interface, having low interfacial trap densities, comparable to its MBE counterpart, shedding light on the realization of high performance Sb-based devices.

*Y. H. Lin and K. Y. Lin have made equal contributions to this work.


Keywords: Atomic Layer Deposition, GaSb, III-V compound semiconductor, Interface