Characterization of β-Ga2O3 and device fabrication

Enora Vuillermet, Changzi Lu, Camille Sonneville, Pierre Brosselard,
Jean-Marie Bluet, Dominique Planson

► To cite this version:

Enora Vuillermet, Changzi Lu, Camille Sonneville, Pierre Brosselard, Jean-Marie Bluet, et al.. Characterization of β-Ga2O3 and device fabrication. Société Française de Physique, Jun 2025, Troyes, France. hal-05099267

HAL Id: hal-05099267

https://hal.science/hal-05099267v1

Submitted on 11 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.

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

Distributed under a Creative Commons Attribution 4.0 International License
# Characterization of β-Ga₂O₃

Enora Vuillermet¹, Changzi Lu¹,², Pierre Brosselard¹, Jean-Marie Bluet², Camille Sonneville¹

¹ INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, CNRS, Ampère, UMR5005, F-69622, France

² INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale Lyon, CPE, CNRS, Institut des Nanotechnologies de Lyon, UMR5270, F-69622, France

Corresponding author: enora.vuillermet@insa-lyon.fr

## Introduction

β-Ga₂O₃ : monoclinic lattice → weak symmetry

* Two different cell units : Ga₁O₄ and GaⅡO₆

* Anisotropy of electrical and optical properties

* Applications in power devices and UV photodetectors

**Objectives** : Raman/PL characterization of β-Ga₂O₃ to better understand the effects of material defects and substrate orientation on β-Ga₂O₃ power devices electrical performance

* **Identification of β-Ga₂O₃**

* **Defect & stress distribution**

<figure><img src="image_2.png" /></figure>

Houqiang Fu et al, *IEEE T-ED*, 65, 2018

<figure><img src="image_3.png" /></figure>

## Identification of substrates

### Raman spectra of β-Ga₂O₃ substrates with green laser

* Low influence of doping on the spectra : small variation for Sn doping (type n)

* The orientation of the substrate affects the Raman spectra

* The stress influences the position of the Raman peaks

<figure><img src="image_4.png" /></figure>

Substrates with different types of doping

<figure><img src="image_5.png" /></figure>

Different orientations of substrates

Raman/PL measurements :
Renishaw micro-spectrometer

* Raman : laser 532nm and 325nm

* PL : laser 325nm

<figure><img src="image_6.png" /></figure>

* Three different groups of Raman peaks

## Defect and stress distribution in substrates

### Raman mappings with green laser

<figure><img src="image_7.png" /></figure>

Raman measurements :

* The Ag³ peak position shift (Δω) can be expressed as a function of tensile stress (σT) within the sample by the formula : $Δω = -0.33σT$

(Noriyuki Hasuike et al, JJAP, 62, 2023)

* Relative homogeneous stress in the substrate

* Some stress at the borders of the sample

### Fe-doped β-Ga₂O₃
substrate

<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

Mapping of the band at 800nm

### PL mappings with UV laser

* Red luminescence → Cr³⁺ impurities or DAP recombination N₀-V₀

* The band at 800nm is thinner and blue-shifted at the center of the sample

## Defect identification in epitaxial layers

### Defects in β-Ga₂O₃ epitayer

<figure><img src="image_10.png" /></figure>

### Raman mapping with UV laser

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

Mapping of Ag⁷ peak

* Localization of structural defects with Raman measurements

<figure><img src="image_13.png" /></figure>

### PL mapping with UV laser

<figure><img src="image_14.png" /></figure>

Mapping of the band at 430nm

* Identification of point defects distribution along the defect with PL measurements

* Band around 425nm → divacancy (V₇ₐ + V₀)¹⁻

* Green luminescence : divided opinion in the literature → Ga or O vacancy or a still unknown extended defect

## Conclusion and perspectives

* β-Ga₂O₃ monoclinic lattice leads to the weak symmetry of the crystal → the orientation of the substrate affects the Raman spectra

* Doping has little to no effect on Raman measurements

* Stress at the border of the substrate can be identified with Raman mapping

* PL measurements allow the location of point defects within the samples that are not visible with Raman

**Future work** : conception of a Schottky diode in β-Ga₂O₃ to study the effects of material defects on electronic devices performances

<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /></figure>

<figure><img src="image_17.png" /></figure>

<figure><img src="image_18.png" /></figure>

<figure><img src="image_19.png" /></figure>

<figure><img src="image_20.png" /></figure>

Université Claude Bernard

<figure><img src="image_21.png" /></figure>

Lyon 1

<figure><img src="image_22.png" /></figure>

ÉCOLE
CENTRALE LYON

<figure><img src="image_23.png" /></figure>

INSTITUT NATIONAL
DES SCIENCES
APPLIQUÉES
LYON