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Title: Band alignment between GaN and ZrO{sub 2} formed by atomic layer deposition

Abstract

The band alignment between Ga-face GaN and atomic-layer-deposited ZrO{sub 2} was investigated using X-ray photoelectron spectroscopy (XPS). The dependence of Ga 3d and Zr 3d core-level positions on the take-off angles indicated upward band bending at GaN surface and potential gradient in ZrO{sub 2} layer. Based on angle-resolved XPS measurements combined with numerical calculations, valence band discontinuity ΔE{sub V} of 1 ± 0.2 eV and conduction band discontinuity ΔE{sub C} of 1.2 ± 0.2 eV at ZrO{sub 2}/GaN interface were determined by taking GaN surface band bending and potential gradient in ZrO{sub 2} layer into account.

Authors:
; ; ; ; ;  [1];  [2]
  1. Novitas, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
  2. Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore 138602 (Singapore)
Publication Date:
OSTI Identifier:
22311080
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DEPOSITION; GALLIUM NITRIDES; INTERFACES; LAYERS; NUMERICAL SOLUTION; SURFACES; VALENCE; X-RAY PHOTOELECTRON SPECTROSCOPY; ZIRCONIUM OXIDES

Citation Formats

Ye, Gang, Wang, Hong, E-mail: ewanghong@ntu.edu.sg, Arulkumaran, Subramaniam, Ng, Geok Ing, Li, Yang, Ang, Kian Siong, and Liu, Zhi Hong. Band alignment between GaN and ZrO{sub 2} formed by atomic layer deposition. United States: N. p., 2014. Web. doi:10.1063/1.4890470.
Ye, Gang, Wang, Hong, E-mail: ewanghong@ntu.edu.sg, Arulkumaran, Subramaniam, Ng, Geok Ing, Li, Yang, Ang, Kian Siong, & Liu, Zhi Hong. Band alignment between GaN and ZrO{sub 2} formed by atomic layer deposition. United States. doi:10.1063/1.4890470.
Ye, Gang, Wang, Hong, E-mail: ewanghong@ntu.edu.sg, Arulkumaran, Subramaniam, Ng, Geok Ing, Li, Yang, Ang, Kian Siong, and Liu, Zhi Hong. Mon . "Band alignment between GaN and ZrO{sub 2} formed by atomic layer deposition". United States. doi:10.1063/1.4890470.
@article{osti_22311080,
title = {Band alignment between GaN and ZrO{sub 2} formed by atomic layer deposition},
author = {Ye, Gang and Wang, Hong, E-mail: ewanghong@ntu.edu.sg and Arulkumaran, Subramaniam and Ng, Geok Ing and Li, Yang and Ang, Kian Siong and Liu, Zhi Hong},
abstractNote = {The band alignment between Ga-face GaN and atomic-layer-deposited ZrO{sub 2} was investigated using X-ray photoelectron spectroscopy (XPS). The dependence of Ga 3d and Zr 3d core-level positions on the take-off angles indicated upward band bending at GaN surface and potential gradient in ZrO{sub 2} layer. Based on angle-resolved XPS measurements combined with numerical calculations, valence band discontinuity ΔE{sub V} of 1 ± 0.2 eV and conduction band discontinuity ΔE{sub C} of 1.2 ± 0.2 eV at ZrO{sub 2}/GaN interface were determined by taking GaN surface band bending and potential gradient in ZrO{sub 2} layer into account.},
doi = {10.1063/1.4890470},
journal = {Applied Physics Letters},
number = 2,
volume = 105,
place = {United States},
year = {Mon Jul 14 00:00:00 EDT 2014},
month = {Mon Jul 14 00:00:00 EDT 2014}
}
  • Influence of post-deposition annealing on interfacial properties related to the formation/annihilation of interfacial GaO{sub x} layer of ZrO{sub 2} grown by atomic layer deposition (ALD) on GaN is studied. ZrO{sub 2} films were annealed in N{sub 2} atmospheres in temperature range of 300 °C to 700 °C and analyzed by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. It has been found that Ga-O bond to Ga-N bond area ratio decreases in the samples annealed at temperatures lower than 500 °C, which could be attributed to the thinning of GaO{sub x} layer associated with low surface defect states due to “clean up” effectmore » of ALD-ZrO{sub 2} on GaN. However, further increase in annealing temperature results in deterioration of interface quality, which is evidenced by increase in Ga-O bond to Ga-N bond area ratio and the reduction of Ga-N binding energy.« less
  • The energy band alignment between atomic layer deposited (ALD) SiO{sub 2} and β-Ga{sub 2}O{sub 3} (2{sup ¯}01) is calculated using x-ray photoelectron spectroscopy and electrical measurement of metal-oxide semiconductor capacitor structures. The valence band offset between SiO{sub 2} and Ga{sub 2}O{sub 3} is found to be 0.43 eV. The bandgap of ALD SiO{sub 2} was determined to be 8.6 eV, which gives a large conduction band offset of 3.63 eV between SiO{sub 2} and Ga{sub 2}O{sub 3}. The large conduction band offset makes SiO{sub 2} an attractive gate dielectric for power devices.
  • The effect of post-deposition annealing on chemical bonding states at interface between Al{sub 0.5}Ga{sub 0.5}N and ZrO{sub 2} grown by atomic layer deposition (ALD) is studied by angle-resolved x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. It has been found that both of Al-O/Al 2p and Ga-O/Ga 3d area ratio decrease at annealing temperatures lower than 500 °C, which could be attributed to “clean up” effect of ALD-ZrO{sub 2} on AlGaN. Compared to Ga spectra, a much larger decrease in Al-O/Al 2p ratio at a smaller take-off angle θ is observed, which indicates higher effectiveness of the passivation of Al-O bondmore » than Ga-O bond through “clean up” effect near the interface. However, degradation of ZrO{sub 2}/AlGaN interface quality due to re-oxidation at higher annealing temperature (>500 °C) is also found. The XPS spectra clearly reveal that Al atoms at ZrO{sub 2}/AlGaN interface are easier to get oxidized as compared with Ga atoms.« less
  • The valence band offset, {Delta}E{sub V}, at an Al{sub 2}O{sub 3}/In{sub 0.17}Al{sub 0.83}N interface formed by atomic layer deposition was measured by x-ray photoelectron spectroscopy. The conventional method of using the core level separation, {Delta}E{sub CL}, between O 1s and In 4d resulted in {Delta}E{sub V} = 1.3 eV, which was apparently consistent with the direct observation of the valence band edge varying the photoelectron exit angle, {theta}. However, {Delta}E{sub CL} and full width at half maximum of core-level spectra were dependent on {theta}, which indicated significant potential gradients in Al{sub 2}O{sub 3} and InAlN layers. An actual {Delta}E{sub V}more » of 1.2 eV was obtained considering the potential gradients.« less
  • Al{sub 2}O{sub 3} films were prepared by atomic layer deposition using trimethylaluminum and H{sub 2}O at 250 Degree-Sign C on 4H-SiC substrates and annealed at 1000 Degree-Sign C in N{sub 2}. The as-deposited and annealed Al{sub 2}O{sub 3} films were measured and analyzed near the Al{sub 2}O{sub 3}/SiC interfaces by using an X-ray photoelectron spectroscopy (XPS) with etching processing. The XPS results showed that as-deposited Al{sub 2}O{sub 3} films were O-rich and converted to anhydride Al{sub 2}O{sub 3} films after annealed at 1000 Degree-Sign C in N{sub 2}. Si suboxides were found both at as-deposited and annealed Al{sub 2}O{sub 3}/SiCmore » interfaces. Energy band shift between Al{sub 2}O{sub 3} and 4H-SiC was found after annealing. The conduction band offsets of as-grown and annealed Al{sub 2}O{sub 3}/SiC were 1.90 and 1.53 eV, respectively. These results demonstrated that Al{sub 2}O{sub 3} can be a good candidate to be applied in SiC metal-oxide-semiconductor devices.« less