Low temperature Ga2O3 atomic layer deposition using gallium tri-isopropoxide and water (original) (raw)
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Chemical Vapor Deposition of Ga2O3 Thin Films on Si Substrates
Bulletin of The Korean Chemical Society, 2002
Amorphous Ga 2 O 3 films have been grown on Si(100) substrates by metal organic chemical vapor deposition (MOCVD) using gallium isopropoxide, Ga(O i Pr) 3 , as single precursor. Deposition was carried out in the substrate temperature range 400-800 °C. X-ray photoelectron spectroscopy (XPS) analysis revealed deposition of stoichiometric Ga 2 O 3 thin films at 500-600 °C. XPS depth profiling by Ar + ion sputtering indicated that carbon contamination exists mostly in the surface region with less than 3.5% content in the film. Microscopic images of the films by scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed formation of grains of approximately 20-40 nm in size on the film surfaces. The root-mean-square surface roughness from an AFM image was ∼10 A. The interfacial layer of the Ga 2 O 3 /Si was measured to be ∼35 A thick by cross-sectional transmission electron microscopy (TEM). From the analysis of gaseous products of the CVD reaction by gas chromatography-m...
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.
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.
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.
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.
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.
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.
Gadolinium oxide thin films by atomic layer deposition
Journal of Crystal Growth, 2005
Gadolinium oxide thin films have been deposited on Si(1 0 0) by atomic layer deposition (ALD) using as precursors either a b-diketonate-type chelate, namely Gd(thd) 3 (thd ¼ 2,2,6,6-tetramethyl-3,5-heptanedione) and ozone or a true organometallic (CpCH 3 ) 3 Gd (Cp ¼ cyclopentadienyl, ÀC 5 H 5 ) together with water. Self-limiting ALD growth mode was detected for the Gd(thd) 3 /O 3 process at 300 1C with a growth rate of 0.3 Å /cycle. In the case of the (CpCH 3 ) 3 Gd/ H 2 O process, partial decomposition of the metal precursor affected the film growth mechanism. However, at 250 1C, the uniform films obtained from (CpCH 3 ) 3 Gd and H 2 O showed almost an ideal stoichiometry with low impurity contents (e.g. 0.5 at% of C) as analyzed by time-of-flight elastic recoil detection analysis (TOF-ERDA). X-ray diffraction data indicated that Gd 2 O 3 films obtained by the Cp-based process were crystalline with cubic C-type structure when deposited even at 150 1C. The strongest reflection changed from (4 0 0) to (2 2 2) at deposition temperatures around 200 1C. Oxygen-rich films grown by the Gd(thd) 3 /O 3 process were amorphous at deposition temperatures below 250 1C but crystalline with (4 0 0) dominant reflection at temperatures exceeding 250 1C. The films were smooth with both processes at the optimized deposition temperatures. In addition, the dielectric properties were analyzed showing effective permittivity of about 13 for the (CpCH 3 ) 3 Gd/H 2 O-processed Gd 2 O 3 films. r
Applied Physics Letters, 2004
Structural, electronic, and optical properties of amorphous and transparent zinc tin oxide films deposited on glass substrates by pulsed laser deposition ͑PLD͒ were examined for two chemical compositions of Zn: Sn=1:1 and 2:1 as a function of oxygen partial pressure ͑P O 2 ͒ used for the film deposition and annealing temperature. Different from a previous report on sputter-deposited films ͓Chiang et al., Appl. Phys. Lett. 86, 013503 ͑2005͔͒, the PLD-deposited films crystallized at a lower temperature Ͻ450°C to give crystalline ZnO and SnO 2 phases. The optical band gaps ͑Tauc gaps͒ were 2.80− 2.85 eV and almost independent of oxygen P O 2 , which are smaller than those of the corresponding crystals ͑3.35− 3.89 eV͒. Films deposited at low P O 2 showed significant subgap absorptions, which were reduced by postthermal annealing. Hall mobility showed steep increases when carrier concentration exceeded threshold values and the threshold value depended on the film chemical composition. The films deposited at low P O 2 Ͻ 2 Pa had low carrier concentrations. It is thought that the low P O 2 produced high-density oxygen deficiencies and generated electrons, but these electrons were trapped in localized states, which would be observed as the subgap absorptions. Similar effects were observed for 600°C crystallized films and their resistivities were increased by formation of subgap states due to the reducing high-temperature condition. High carrier concentrations and large mobilities were obtained in an intermediate P O 2 region for the as-deposited films.
Evaluation of the crystalline quality of β-Ga2O3 films by optical absorption measurements
Physica B: Condensed Matter, 2009
Si doped b-Ga 2 O 3 films were grown on Si substrate by RF magnetron sputtering. The Si concentration varied from 0% to 50%. After the deposition of the amorphous Ga 2 O 3 on the substrate, thermal annealing at 600 1C was performed in nitrogen ambient. Polycrystalline b-Ga 2 O 3 films were grown on Si or quartz substrates; however, other mixed phases of Si, Ga and O were not observed. From the measurement of optical absorption coefficient, it is concluded that the b-Ga 2 O 3 energy gap increases with increasing Si concentration in the deposited film.