Chemical Vapor Deposition of Ga2O3 Thin Films on Si Substrates (original) (raw)

Low temperature Ga2O3 atomic layer deposition using gallium tri-isopropoxide and water

Thin Solid Films, 2013

Ga 2 O 3 atomic layer deposition (ALD) was carried out using gallium tri-isopropoxide (GTIP) as a gallium source and H 2 O as an oxygen source at a low temperature (150°C). The Ga 2 O 3 ALD films show amorphous, smooth, and transparent behavior. The growth behavior and a variety of optical, structural, and electrical properties were investigated by various measurements. The growth behavior of Ga 2 O 3 ALD using GTIP reveals a typical ALD process, and Ga 2 O 3 films on glass substrates show outstanding transmittance (over 90%). The Ga:O ratio was measured as 1:1.7 by the Rutherford backscattering spectrometry, and auger electron spectroscopy confirmed that there was no carbon impurity (under the detection limit). The surface morphology was investigated through an atomic force microscope analysis, and all of the films deposited at 150, 200, and 250°C showed smooth and featureless characteristics. Ga 2 O 3 ALD thin film shows excellent leakage current (1 × 10 −11 A at 1 MV/cm) and a very suitable breakdown field (6.5-7.6 MV/cm) as compared to previously reported Ga 2 O 3 films. Also, the dielectric constant of the films is similar to that of conventional Ga 2 O 3 films (about 9.23).

Experimental and Theoretical Validation of Ga2O3 Thin Films Deposited by Physical Vapor Deposition

2019 International Semiconductor Conference (CAS), 2019

In this work, we have shown that betagallium oxide (Ga2O3) thin films of differing thickness could be obtained by physical vapor deposition method, employing proper annealing conditions. These enable us to compare the variation of optical properties like transparency, band gap in these phases. Apart from these, our analysis of transmittance spectra of beta-Ga2O3 indicated the reduction of structural disorders (amorphous to crystalline) with increase in annealing temperature. The calculated band gap based on Density Functional Theory (DFT) for bulk beta-Ga2O3 thin films ~ 4.9 eV (direct) at room temperature is in excellent agreement with our experimentally measured values. This work will serve as design guidance for the new Ga2O3 based thin film electronics.

Atomic Layer Deposition of Ga 2 O 3 Films from a Dialkylamido-Based Precursor

Chemistry of Materials, 2006

The atomic layer deposition growth of Ga 2 O 3 films was demonstrated using Ga 2 (NMe 2 ) 6 and water with substrate temperatures between 150 and 300°C. At 250°C, surface saturative growth was achieved with Ga 2 (NMe 2 ) 6 vapor pulse lengths of g1.5 s. The growth rate was 1.0 Å/cycle at substrate temperatures between 170 and 250°C. Growth rates of 1.1 and 0.89 Å/cycle were observed at 150 and 275°C, respectively. In a series of films deposited at 250°C, the film thicknesses varied linearly with the number of deposition cycles. Time-of-flight elastic recoil detection analyses demonstrated stoichiometric Ga 2 O 3 films, with carbon, hydrogen, and nitrogen levels between 1 and 2.1, 4.8-5.4, and 0.6-0.9 at. %, respectively, at substrate temperatures of 170, 200, and 250°C. The as-deposited films were amorphous, but crystallized to -Ga 2 O 3 films upon annealing between 700 and 900°C under a nitrogen atmosphere. Atomic force microscopy showed root-mean-square surface roughnesses of 0.4 and 0.6 nm for films deposited at 170 and 250°C, respectively.

Experimental analysis of Ga2O3:Ti films grown on Si and glass substrates

Microelectronics Reliability, 2013

Ti-included gallium oxide (Ga 2 O 3 :Ti) thin films were prepared on glass and silicon substrates. The energy dispersion X-ray spectroscopy (EDX) method was used to measure the Ti inclusion level, which was 1.0%, 1.5%, 2.0%, 4.2%, 6.6%, 10.4%, 15.7%, and 27.6%. The X-ray diffraction (XRD) method was used to study the crystalline structure of the films. The oxide films grown on silicon substrate have amorphous structure while those oxide films grown on glass substrate show crystalline Ga 2 O 3 structure, which confirms that the titanium was dissolved in the lattice of Ga 2 O 3 forming solid solution (SS). The insulating properties of the amorphous Ti-included Ga-oxide films were studied for samples made in form of MOS:Au/Ga 2 O 3 :Ti/Si configuration. It was observed that Ti inclusion of certain levels reduces the effective dielectric constant of Ga 2 O 3 :Ti film to less than that of SiO 2 , i.e. the inclusion of Ti turns the high-k gallium oxide dielectric into low-k insulator. The dielectric relaxation of the incorporated films was studied through the complex dielectric modulus M ⁄ , from which the high-frequency dielectric constant e 0 1 and the most probable relaxation time (s) as a function of Ti-inclusion level was determined. The optosensitivity of Ga 2 O 3 :Ti film was studied as a function of Ti inclusion. The temperature dependent of the dc-current leaks through Au/ Ga 2 O 3 :Ti/Si, MOS arrangement predicts a red shift of the bandgap due to Ti doping.

Transition from thin film to nanostructure in low pressure chemical vapor deposition growth of β-Ga2O3: Impact of metal gallium source

Thin Solid Films, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

H2O vapor assisted growth of β-Ga2O3 by MOCVD

AIP Advances, 2020

The role of water (H2O) vapor in reducing background impurity concentration in epitaxial Ga2O3 thin films grown by metalorganic chemical vapor deposition (MOCVD) was studied. Adding H2O vapor to oxygen was found to increase the surface roughness and decrease the carrier concentration but have no effect on the structural quality and RT electron mobility of both the UID and doped films. The H2O vapor promotes the growth of the stable (110) and 1¯10 facets elongated along the [001] direction. Using [H2O] of 250 ppm, the β-Ga2O3 films showed a RMS roughness of >13 nm, which is much higher than that measured for similar films grown without H2O (RMS = 0.8 nm). The electron mobility of the UID Ga2O3 layers grown with and without water vapor was ∼150 cm2/V s, while the carrier concentration dropped by ∼2.5× after increasing the [H2O] to 6000 ppm. Similarly, for the lightly Si doped films, the RT carrier concentration dropped from 5.4 × 1015 cm−3 ([H2O] = 0 ppm) to 3.4 × 1015 cm−3 ([H2O] ...

Ga2O3 THIN FILM DEPOSITED BY ATOMIC LAYER DEPOSITION WITH HIGH PLASMA POWER

Integrated Ferroelectrics, 2006

Ga 2 O 3 thin films were deposited at 200 • C on p-type Si (100) by plasma-enhanced atomic layer deposition technique with an alternating supply of reactant source, [(CH 3) 2 GaNH 2 ] 3 , and high-power oxygen plasma of 180 W. The as-deposited thin films were annealed at 500, 700, 900 • C in oxygen ambient for 10 min in a rapid thermal annealing system, respectively. X-ray diffractometer and atomic force microscope were used to investigate the structural properties and the surface morphologies of the thin films. The as-deposited thin film was amorphous and the thin films annealed at high temperatures were monoclinic β-phase Ga 2 O 3. The electrical properties of Pt/Ga 2 O 3 /Si structured thin film were investigated using a semiconductor parameter analyzer. It was found that the as-deposited thin film and the thin film annealed at 500 • C were leaky, however, the insulating properties of the thin films annealed at high temperatures were greatly improved. Spectroscopic ellipsometry was also used to derive the refractive indices and the thicknesses of the thin films.

GROWTH TEMPERATURE DEPENDENCE OF Ga2O3 THIN FILMS DEPOSITED BY PLASMA ENHANCED ATOMIC LAYER DEPOSITION

Integrated Ferroelectrics, 2007

In this report, plasma-enhanced atomic layer deposition (PEALD) technique was used to deposit dielectric Ga 2 O 3 thin films at various temperatures (50, 150, and 250 • C) on p-type Si (100) and quartz substrates with an alternating supply of reactant source, [(CH 3) 2 GaNH 2 ] 3 , and oxygen plasma of 150 W. The growth temperature dependences of the Ga 2 O 3 thin films were investigated. An atomic force microscope and an X-ray diffractometer were used to investigate the surface morphologies and the structural properties of the thin films. The electrical properties of Pt/Ga 2 O 3 /Si structured thin film were investigated by using a semiconductor parameter analyzer. A spectrophotometer was used to measure the transmittances of the thin films, and the band gap energies of the thin films were calculated.

Growth Pressure Controlled Nucleation Epitaxy of Pure Phase ε- and β-Ga2O3 Films on Al2O3 via Metal–Organic Chemical Vapor Deposition

Crystal Growth & Design, 2018

Pure εand β-phase gallium oxide (Ga 2 O 3) films has been successfully grown on Al 2 O 3 (001) substrate via metal-organic chemical vapor deposition (MOCVD) at growth temperature of 500 ℃. Growth pressure controlled nucleation is dominant controlling parameter for pure phase Ga 2 O 3 film growth. Due to the biaxial stress induced by lattice mismatch, hetero-epitaxial ε-phase Ga 2 O 3 is grown on Al 2 O 3 by heterogeneous nucleation at low pressure. However, film growth is dominated by spherical nuclei homogeneous nucleation at pressure higher than 100 mbar, and β-phase Ga 2 O 3 film is grown with mosaic surface. The optimum pressure for the growth of pure ε-Ga 2 O 3 films with superior crystallinity is 35 mbar whereas; the pressure window for pure β-Ga 2 O 3 growth is between 100 mbar to 400 mbar. The growth rate of β-Ga 2 O 3 film is much lower than ε-Ga 2 O 3 film at high pressure. On the other, all Ga 2 O 3 films have showed good optical properties with a band gap of about 4.9 eV. This fundamental research will succor to understand the mechanism of MOCVD growth involving high quality and pure phase εand β-Ga 2 O 3 film.

Temperature Dependence of Ultrathin Mixed-Phase Ga2O3 Films Grown on the α-Al2O3 Substrate via Mist-CVD

ACS Omega

Alpha (α)-and beta (β)-phase gallium oxide (Ga 2 O 3), emerging as ultrawideband gap semiconductors, have been paid a great deal of attention in optoelectronics and high-performance power semiconductor devices owing to their ultrawide band gap ranging from 4.4 to 5.3 eV. The hot-wall mist chemical vapor deposition (mist-CVD) method has been shown to be effective for the growth of pure αand β-phase Ga 2 O 3 thin films on the α-Al 2 O 3 substrate. However, challenges to preserve their intrinsic properties at a critical growth temperature for robust applications still remain a concern. Here, we report a convenient route to grow a mixed αand β-phase Ga 2 O 3 ultrathin film on the α-Al 2 O 3 substrate via mist-CVD using a mixture of the gallium precursor and oxygen gas at growth temperatures, ranging from 470 to 700°C. The influence of growth temperature on the film characteristics was systematically investigated. The results revealed that the as-grown Ga 2 O 3 film possesses a mixed αand β-phase with an average value of dislocation density of 10 10 cm −2 for all growth temperatures, indicating a high lattice mismatch between the film and the substrate. At 600°C , the ultrathin and smooth Ga 2 O 3 film exhibited a good surface roughness of 1.84 nm and an excellent optical band gap of 5.2 eV. The results here suggest that the mixed αand β-phase Ga 2 O 3 ultrathin film can have great potential in developing future high-power electronic devices.