Effect of postdeposition annealing on the electrical properties of β-Ga2O3 thin films grown on p-Si by plasma-enhanced atomic layer deposition

Abstract

Ga2O3 dielectric thin films were deposited on (111)-oriented p-type silicon wafers by plasma-enhanced atomic layer deposition using trimethylgallium and oxygen plasma. Structural analysis of the Ga2O3 thin films was carried out using grazing-incidence x-ray diffraction. As-deposited films were amorphous. Upon postdeposition annealing at 700, 800, and 900 °C for 30 min under N2 ambient, films crystallized into β-form monoclinic structure. Electrical properties of the β-Ga2O3 thin films were then investigated by fabricating and characterizing Al/β-Ga2O3/p-Si metal–oxide-semiconductor capacitors. The effect of postdeposition annealing on the leakage current densities, leakage current conduction mechanisms, dielectric constants, flat-band voltages, reverse breakdown voltages, threshold voltages, and effective oxide charges of the capacitors were presented. The effective oxide charges (Qeff) were calculated from the capacitance–voltage (C-V) curves using the flat-band voltage shift and were found as 2.6 × 1012, 1.9 × 1012, and 2.5 × 1012 cm−2 for samples annealed at 700, 800, and 900 °C, respectively. Effective dielectric constants of the films decreased with increasing annealing temperature. This situation was attributed to the formation of an interfacial SiO2 layer during annealing process. Leakage mechanisms in the regions where current increases gradually with voltage were well fitted by the Schottky emission model for films annealed at 700 and 900 °C, and by the Frenkel–Poole emission model for film annealed at 800 °C. Leakage current density was found to improve with annealing temperature. β-Ga2O3 thin film annealed at 800 °C exhibited the highest reverse breakdown field value.

Plasma enhanced atomic layer deposition of gallium oxide on crystalline silicon: demonstration of surface passivation and negative interfacial charge

“…, . Indeed, the values (and polarity) of the charge reported in this study for the Ga 2 O 3 –Si interface are similar to those recently reported by Altuntas et al for crystalline (β‐phase) Ga 2 O 3 on silicon formed by annealing PE‐ALD films at elevated temperatures (≥700 °C), though the authors in that study were unable to obtain CV data for un‐annealed, amorphous Ga 2 O 3 –Si structures .…”

“…Carbon contamination is common for Al 2 O 3 ALD films, and is a remanent from the organic methyl (CH 3 ) ligands common to the trimethyl‐aluminium and trimethyl‐gallium precursors . Altuntas et al also report negligible residual carbon in similarly prepared PE‐ALD Ga 2 O 3 films, as determined by sputter depth profilometry . A small, broad feature in the pre‐annealed sample in the range 2600 cm –1 to 3700 cm –1 (band (d) in the figure) indicates the possible incorporation of hydrogen in the film, in the form of O–H bonds .…”

Study on the Physical and Leakage Current Characteristics of an Optimized High-k/InAlAs MOS Capacitor with a HfO2–Al2O3 Laminated Dielectric

“…We controlled the ALD process circle to manufacture different dielectric thicknesses. A post-deposition annealing (PDA) process was applied to increase the quality of the oxide-semiconductor interface [14][15][16][17]. The process involved heating the film from ambient temperature to 380 • C in N 2 over 15 s, annealing for 60 s , and then cooling to ambient temperature over 300 s [6,7].…”

High Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration

“…[ 1 ] With a wide bandgap of ≈4.7–4.9 eV and excellent chemical and physical stability, gallium oxide (Ga 2 O 3 ) has become an attractive choice of material for UV‐C photodetectors (PDs). [ 2 ] The unique combination of high bandgap and ability to extrinsically n ‐type‐doped Ga 2 O 3 has led to a measurable interest in studying a wide range of prospective heterostructure combinations, such as MgZnO/Ga 2 O 3 , [ 3 ] Ga 2 O 3 /GaN, [ 4 ] Ga 2 O 3 /SiC, [ 5 ] and Ga 2 O 3 /Si, [ 6–14 ] for use as UV PDs. Among these heterojunctions, Ga 2 O 3 /Si is especially attractive due to the well‐known cost and availability advantages of Si substrates, and its prominent applications in Si‐based optoelectronic integrated circuits.…”

“…n ‐type β‐Ga 2 O 3 nanobelts contacted onto p ‐Si substrate have also been explored for UV‐C PDs. [ 10 ] Amorphous Ga 2 O 3 ‐based PDs have also been demonstrated on silicon substrates using atomic layer deposition (ALD) [ 11,12,14 ] and metal–organic chemical vapor deposition (MOCVD). [ 15 ]…”