Photoemission of the SiO2–SiC heterointerface

Abstract

Photoelectron spectroscopy has been performed on SiC surfaces to investigate the valence band characteristics during SiO2 formation. Various stages of the oxide development were investigated. The √3×√3R30° surface is used as the initial surface for the oxidation experiments. The substrates were exposed to a succession of a 30 s oxygen exposure, two 30 s oxygen plasmas, and finally, a plasma-enhanced chemical vapor deposition SiO2 deposition. Ultraviolet photoemission spectroscopy was employed to measure the valence band discontinuity for the oxide on n-type 6H and n-type 4H SiC substrates for each step in the oxidation process. X-ray photoemission spectroscopy was used to confirm the valence band offset. The valence band discontinuity was determined to be 2.0 eV. Furthermore, the location of the valence band maximum of the SiC to the conduction band minimum of the SiO2 is determined to be a constant (∼7.0 eV) between 6H and 4H SiC. Band bending effects are directly measured from ultraviolet photoemission spectroscopy (UPS) and x-ray photoemission spectroscopy. From the UPS measurements of the band bending effects, the interface state density is determined to be ∼5×1012 cm−2.

Crystalline BeO Grown on 4H-SiC via Atomic Layer Deposition: Band Alignment and Interface Defects

“…The localized UPS data on the turn-on point are shown in Figure S3. By use of the method, the VBM position of as-cleaned 4H-SiC is deduced as 2.43 ± 0.01 eV in Figure a, and this is similar to the reported values (2.6 eV for n-type 4H-SiC) . The VBM values of oxide samples are 4.96 ± 0.01 eV for ALD BeO, 4.09 ± 0.01 eV for ALD Al 2 O 3 , and 5.03 ± 0.01 eV for PECVD SiO 2 .…”

“…By use of the method, the VBM position of as-cleaned 4H-SiC is deduced as 2.43 ± 0.01 eV in Figure 6a, and this is similar to the reported values (2.6 eV for n-type 4H-SiC). 34 The VBM values of oxide samples are 4.96 ± 0.01 eV for ALD BeO, 4.09 ± 0.01 eV for ALD Al 2 O 3 , and 5.03 ± 0.01 eV for PECVD SiO 2 . The VBO is calculated by 35,36 Therefore, the VBO of ALD BeO/SiC obtained in the study is also considered as reasonable.…”

Thermal evaporation synthesis of SiC/SiOx nanochain heterojunctions and their photoluminescence properties

“…SiC/SiO 2 nanochain heterojunction has attracted much attention since it can combine the unique properties of SiC and SiO x . 18,19 Up to now, several preparation methods have been used to synthesize the SiC/SiO 2 nanochain heterojunction. Li et al 6 prepared SiC/SiO 2 chainlike nanostructures via a template/catalyst-free chemical vapor reaction process using Si-SiO 2 mixture powder and CH 4 as raw materials at 1200-1250 C. Wei et al 20 obtained 1-D SiC/SiO 2 nanochain heterojunctions via a microwave method using tetraethoxysilane, Si and charcoal as raw materials.…”

Atomic Structure of SiC Surfaces

“…• structure were investigated by UPS and XPS [134,135]. Atomic level experimental and theoretical investigations are now also focussing on the structural interface properties upon high pressure oxidation [136]- [142].…”