| 1. |
- Horng, Ray-Hua, et al.
(författare)
-
Growth mechanism and characteristics of beta-Ga2O3 heteroepitaxailly grown on sapphire by metalorganic chemical vapor deposition
- 2022
-
Ingår i: Materials Today Advances. - : ELSEVIER. - 2590-0498. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, monoclinic gallium oxide (beta-Ga2O3) epilayer was successfully grown on c-plane, (0001), sapphire substrate by metalorganic chemical vapor deposition (MOCVD) with interplaying growth temperature, TEGa flow rate, and growth time. X-ray diffraction 20 scans show only three narrow diffraction peaks referred to beta-Ga2O3 ((2) over bar 01), ((4) over bar 02), and ((6) over bar 03) in all epilayers, indicating a superior crystalline quality. Current-voltage (I-V) measurement reveals that these beta-Ga2O3 films are insulating and exhibit high resistance in a range of 10(12)-10(14) Omega. The crystallization characteristics of the epilayers can be effectively improved with thickness through increasing TEGa flow rate and growth time, which was evidenced by X-ray rocking curves and I-V measurements. However, the surface roughness of beta-Ga2O3 film increases with growth time and TEGa flow rate. When the growth temperature increases above 825 degrees C, the thickness of beta-Ga2O3 film decreases clearly. Furthermore, it can be found that the growth rate decreased as the growth time increasing. The growth mechanism based on first-principles calculation was proposed as that 3D growth induced by the lattice mismatch between beta-Ga2O3 and sapphire starts at nucleation stage, and follows up a lateral growth promoting a 2D growth after the thick epilayer being grown. In addition, the complex chemical reaction between TEGa and oxygen precursors was unraveled by density function theory calculation. (c) 2022 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
|
|
| 2. |
- Horng, Ray-Hua, et al.
(författare)
-
Ion implantation effects on the characteristics of 8-Ga2O3 epilayers grown on sapphire by MOCVD
- 2022
-
Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 48:24, s. 36425-36432
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the Si-ions implantation technique with different doses from 1 x 1014 to 1 x 1015 cm-2 and dose energy 30, 40 and 50 keV was used to tune the electrical properties in unintentionally doped (UID) 8-Ga2O3 epilayers grown on the sapphire substrates by metalorganic chemical vapor deposition (MOCVD). A high quality UID 8-Ga2O3 epilayers were fabricated using the optimized growth parameters of MOCVD. The UID and Si-ions implanted 8-Ga2O3 epilayers were examined and results were compared with the help of X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Si-ions implantation parameters were also simulated by stopping and range of ions in matter software (SRIM) and actual Si-ions concentration was measured by secondary ions mass spectroscopy. The electrical properties of the implanted 8-Ga2O3 epilayers were measured by transmission length method and Hall measurements. The sheet resistivity for the 8-Ga2O3epilayers with Si-ion dose of 1 x 1014, 6 x 1014 and 1 x 1015 cm-2 were found as 2.047, 0.158 and 0.144 Cd cm, respectively measured by Hall measurements and the electron carrier concentrations for the above doses were 4.39 x 1018, 6.86 x 1018 and 7.98 x 1019 cm-3. From the above results, the ion implantation was demonstrated to effectively reduce the resistivity with the high carrier concentrations.
|
|
