Energy-band alignment of Al2O3 and HfAlO gate dielectrics deposited by atomic layer deposition on 4H–SiC

Abstract

Energy band alignment and band gap of Al2O3 and HfAlO films grown by atomic layer deposition on 4H–SiC were determined using x-ray photoelectron spectroscopy. Al2O3 exhibited a symmetric band profile with a conduction band offset (ΔEC) of 1.88 eV and a valence band offset (ΔEV) of 1.87 eV. HfAlO yielded a smaller ΔEC of 1.16 eV and ΔEV of 1.59 eV. The higher dielectric constant and higher effective breakdown field of HfAlO compared to Al2O3, coupled with sufficient electron and hole barrier heights, makes it a potential dielectric for use on 4H–SiC, and provokes interest in further investigation of HfAlO/4H–SiC properties.

Thermally stable, sub-nanometer equivalent oxide thickness gate stack for gate-first In0.53Ga0.47As metal-oxide-semiconductor field-effect-transistors

“…1(f)) spectrum can be fitted to a single peak located between the Al 2 O 3 and the Al sub-oxide peak 12 and attributed to the conversion of the Al 2 O 3 -AlO x layer into a fully oxidized Hf-O-Al alloy. 13 During this process 0.5 Å of elemental Si is consumed, while additional 2.5 Å is consumed during post-metallization anneal 550 C for 30 min in N 2 . In addition the BE shift of the oxidized-Si peak from the Si 0 2p bulk peak drops from þ3.2 eV to þ2.8 eV (Figs.…”

Effect of N bonding structure in AlON deposited by plasma-assisted atomic layer deposition on electrical properties of 4H-SiC MOS capacitor

“…From this result, the energy band offset between AlON and SiC is considered to be smaller than that between SiO 2 and SiC because the energy band of Al 2 O 3 deposited by ALD is reported to be 1.88 eV. 29) Considering the energy band alignment of the AlON=SiO 2 =SiC structure, the tunnel leakage current through the SiO 2 =AlON from SiC at a high voltage should be determined by the leakage current property of the SiO 2 layer since the thickness of the SiO 2 layer is 10 nm. Thus, at a high applied voltage (above 40 V), the leakage current is considered to include the tunnel leakage component.…”

Reduction of interface states by hydrogen treatment at the aluminum oxide/4H-SiC Si-face interface

“…The gate voltage was swept up and down twice at a rate of approximately ±0.03 V/s. The gate leakage current was very large compared with the theoretical FowlerNordheim current, assuming a conduction band offset of Al 2 O 3 /SiC (1.9 eV) 11 and the relative dielectric constant of Al 2 O 3 (7.8). 20 The C-V system was used to evaluate the quasi-static capacitance from the measured charge with elimination of the leakage current component; however, the capacitance cannot be accurately evaluated when most of the measured charge originates from the leakage current.…”

“…For example, aluminum oxide is a promising alternative due to its wide band gap and high dielectric constant. [9][10][11] Although aluminum oxide has been investigated as a gate insulator on SiC, [12][13][14][15][16][17][18] reports on metal-oxide-semiconductor field-effect transistors (MOSFETs) are limited. [16][17][18] Although a considerably large peak field-effect mobility (µ FE ) was reported, the mobility decreases sharply with an increase in the gate voltage.…”