# Pulsed-Liquid Injection MOCVD of epitaxial Ga2O3 thin films

Marielena Velasco Enriquez, Isabelle Gélard, Carmen Jiménez, Herve Roussel, Sonia Ortega-Murillo, Laetitia Rapenne, Philippe Ferrandis, Eirini Sarigiannidou, Vincent Consonni

► To cite this version:

Marielena Velasco Enriquez, Isabelle Gélard, Carmen Jiménez, Herve Roussel, Sonia Ortega-Murillo, et al.. Pulsed-Liquid Injection MOCVD of epitaxial Ga2O3 thin films. EUROCVD & ALD 24, Jun 2025, Catania, Italy. [hal-05176084](https://hal.univ-grenoble-alpes.fr/hal-05176084v1)

HAL Id: hal-05176084

https://hal.univ-grenoble-alpes.fr/hal-05176084v1

Submitted on 22 Jul 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

Public Domain
# Pulsed-Liquid Injection MOCVD of epitaxial $Ga_2O_3$ thin films

M. Velasco Enriquez¹,², I. Gelard¹, C. Jimenez¹, H. Roussel¹, S. Ortega¹, L. Rapenne¹, P. Ferrandis², E. Sarigiannidou¹, and V. Consonni¹

¹Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France

²Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, France

e-mail: marielena.velasco-enriquez@grenoble-inp.fr

The epitaxial growth of $Ga_2O_3$ thin films has emerged as a critical topic for power electronics due to its promising properties (ultra-wide bandgap of 4.8-4.9 eV, breakdown field of 8MV/cm, etc.). Among several growth methods, MOCVD is a great technique for industrial-scale production as it can achieve high growth rates compared to their counterparts [1]. Gallium oxide can exist in several polymorphs: β, α, γ, δ, κ, with the monoclinic β-phase being the most thermodynamically stable one. The influence of MOCVD growth parameters were reported not only to improve growth rates (with tradeoff in crystal quality) of β-$Ga_2O_3$ on sapphire [2], but also to optimize the presence of other polymorphs, for instance κ-$Ga_2O_3$ [3], [4], [5].

Beyond metal-organic chemical vapor deposition (MOCVD) equipped with a bubbler system for introducing the chemical precursors, the pulsed-liquid injection MOCVD technique comprises a vaporizer allowing the utilization of low vapor pressure and thermally unstable chemical precursors: these precursors are introduced in micro-amounts into the evaporator using pulses [6]. In-house studies have shown some key advantages of using this innovative technique in the growth of different materials, as it prevented accumulation of condensed precursor of high-k oxides [7] and it allowed a more controlled morphology and polarity transitions of ZnO [8].

<figure><img src="image_1.png" /></figure>

<figure><img src="image_2.png" /><figcaption>Fig. 1. XRD patterns of (a) β-$Ga_2O_3$ and (b) β/(κ)-$Ga_2O_3$ thin films grown at different substrate temperatures by PLI-MOCVD on sapphire.</figcaption></figure>

In this work, we grow $Ga_2O_3$ thin films on c-plane sapphire by PLI-MOCVD using a semi-industrial ANNEALSYS MC200 reactor with triethyl Gallium (TEGa) and $O_2$ gas. The presence of pure β- or mixed β/κ-$Ga_2O_3$ (Fig. 1) was achieved by varying the substrate temperature, and VI/III ratio. Additionally, the epitaxial quality, nature of defect levels, and interface properties were characterized by SEM, AFM, XPS, TEM, X-ray diffraction, Raman spectroscopy, and cathodoluminescence
spectroscopy. The present findings open perspectives for the growth of epitaxial $Ga_2O_3$ thin films with a
high quality using PLI-MOCVD.

*This work was supported by the French National Research Agency in the framework of the
"Investissements d'avenir" program (ANR-15-IDEX-02)*

**References**

[1] A. Waseem, Z. Ren, H.-C. Huang, K. Nguyen, X. Wu, and X. Li, "A Review of Recent Progress in β-Ga₂O₃ Epitaxial Growth: Effect of Substrate Orientation and Precursors in Metal-Organic Chemical Vapor Deposition," *Physica Status Solidi (a)*, vol. 220, no. 8, p. 2200616, Apr. 2023, doi: 10.1002/pssa.202200616.

[2] F. Alema, B. Hertog, A. Osinsky, P. Mukhopadhyay, M. Toporkov, and W. V. Schoenfeld, "Fast growth rate of epitaxial β-Ga₂O₃ by close coupled showerhead MOCVD," *Journal of Crystal Growth*, vol. 475, pp. 77-82, Oct. 2017, doi: 10.1016/j.jcrysgro.2017.06.001.

[3] Y. Zhuo, Z. Chen, W. Tu, X. Ma, Y. Pei, and G. Wang, "β-Ga₂O₃ versus ε-Ga₂O₃: Control of the crystal phase composition of gallium oxide thin film prepared by metal-organic chemical vapor deposition," *Applied Surface Science*, vol. 420, pp. 802-807, Oct. 2017, doi: 10.1016/j.apsusc.2017.05.241.

[4] Y. Chen, X. Xia, H. Liang, Q. Abbas, Y. Liu, and G. Du, "Growth Pressure Controlled Nucleation Epitaxy of Pure Phase ε- and β-Ga₂O₃ Films on Al₂O₃ via Metal-Organic Chemical Vapor Deposition," *Crystal Growth & Design*, vol. 18, no. 2, pp. 1147-1154, Feb. 2018, doi: 10.1021/acs.cgd.7b01576.

[5] E. Dobročka et al., "Structure and Thermal Stability of ε/κ-Ga₂O₃ Films Deposited by Liquid-Injection MOCVD," *Materials*, vol. 16, no. 1, Art. no. 1, Jan. 2023, doi: 10.3390/ma16010020.

[6] "PROCEDE ET DISPOSITIF D'INTRODUCTION DE PRECURSEURS DANS UNE ENCEINTE DE DEPOT CHIMIQUE EN PHASE VAPEUR (Brevets) - Data INPI." Accessed: Nov. 27, 2023. [Online]. Available: https://data.inpi.fr/brevets/FR2707671?q=#FR2707671

[7] C. Dubourdieu et al., "Pulsed liquid-injection MOCVD of high-K oxides for advanced semiconductor technologies," *Materials Science and Engineering: B*, vol. 118, no. 1-3, pp. 105-111, Apr. 2005, doi: 10.1016/j.mseb.2004.12.019.

[8] Q. C. Bui et al., "Morphology Transition of ZnO from Thin Film to Nanowires on Silicon and its Correlated Enhanced Zinc Polarity Uniformity and Piezoelectric Responses," *ACS Appl. Mater. Interfaces*, vol. 12, no. 26, pp. 29583-29593, Jul. 2020, doi: 10.1021/acsami.0c04112.