# Characterization of silicon vacancies and divacancies in hexagonal silicon carbide formed by nitrogen and aluminum ion implantation

Enora Marion Vuillermet, Nicolas Bercu, Florence Etienne, Mihai Lazar, Louis Giraudet

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## ► To cite this version:

Enora Marion Vuillermet, Nicolas Bercu, Florence Etienne, Mihai Lazar, Louis Giraudet. Characterization of silicon vacancies and divacancies in hexagonal silicon carbide formed by nitrogen and aluminum ion implantation. C'Nano 2023: The Nanoscience meeting, Mar 2023, Poitiers, France. .
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Submitted on 26 Jul 2023

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Distributed under a Creative Commons Attribution 4.0 International License
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Enora Vuillermet¹, Nicolas Bercu², Florence Etienne², Mihai Lazar¹, Louis Giraudet²

¹L2n, CNRS EMR 7004, University of Technology of Troyes, Troyes, France

²LRN, U.F.R Sciences exactes et naturelles, University of Reims Champagne-Ardenne, Reims, France

Context and objectives

<figure><img src="image_5.png" /><figcaption>4H-SiC wafer and crystallography</figcaption></figure>

SiC is a wide bandgap semiconductor with :

* High thermal conductivity, chemical inertness and high critical electrical field [1]

* High technology maturity →control of defects possible [2]

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

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Controlled generation of point defects (color centers) in SiC

* Emission of NIR light

* Single quantum emitters : quantum applications [3]

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Objective : Determination of the optimal ion implantation parameters to generate silicon vacancies ($V_{Si}$) and di-vacancies ($V_c V_{Si}$) in 4H-SiC

Ion implantation allows :

* Simulations close from the experimental results

* A control of the point defects depth in the material

* Limited defects in the SiC matrix with well-controlled parameters

* Generation of color centers in localized and large areas [4]

Materials and methods

<figure><img src="image_10.png" /><figcaption>Ion implantation</figcaption></figure>

* N or Al implantations in 4H-SiC 10µm thick epilayer

* Temperature, dose and energy are changed

* Tilt and twist angles are 7 and 90° respectively

<figure><img src="image_11.png" /><figcaption>Ion implantation simulations</figcaption></figure>

I2SiC software based on Montecarlo method and binary collision approximation (BCA) [5]

<figure><img src="image_12.png" /><figcaption>Cathodoluminescence with JEOL SEM</figcaption></figure>

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Realized before and after annealing at 900°C for 15min (80k, 302 l/mm, 15kV, 1nA)

Results and Discussion

<table><caption>I2SiC simulations</caption><thead><tr><th>Name</th><th>Dopant</th><th>Temperature [°C]</th><th>Energy [keV]</th><th>Dose [cm<sup>-2</sup>]</th></tr></thead><tbody><tr><td rowspan="4">A2</td><td rowspan="4">N15</td><td rowspan="4">RT</td><td>400</td><td>6.4E14</td></tr><tr><td>270</td><td>4.6E14</td></tr><tr><td>170</td><td>4E14</td></tr><tr><td>100</td><td>3.8E14</td></tr><tr><td colspan="5">Total: 1.88E15</td></tr><tr><td rowspan="4">A6</td><td rowspan="4">N</td><td rowspan="4">RT</td><td>400</td><td>3.2E12</td></tr><tr><td>270</td><td>2.3E12</td></tr><tr><td>170</td><td>2E12</td></tr><tr><td>100</td><td>1.9E12</td></tr><tr><td colspan="5">Total: 9.4E12</td></tr><tr><td rowspan="4">A9</td><td rowspan="4">Al</td><td rowspan="4">RT</td><td>300</td><td>5.93E12</td></tr><tr><td>190</td><td>2.9E12</td></tr><tr><td>115</td><td>2.08E12</td></tr><tr><td>60</td><td>1.42E12</td></tr><tr><td>25</td><td>6.81E11</td></tr><tr><td colspan="5">Total: 1.3E13</td></tr><tr><td rowspan="5">A12</td><td rowspan="5">N</td><td rowspan="5">RT</td><td>190</td><td>5.6E12</td></tr><tr><td>135</td><td>3.6E12</td></tr><tr><td>90</td><td>3.4E12</td></tr><tr><td>50</td><td>3.2E12</td></tr><tr><td>30</td><td>2.2E12</td></tr><tr><td colspan="5">Total: 1.8E13</td></tr><tr><td rowspan="5">A16</td><td rowspan="5">N</td><td rowspan="5">300</td><td>160</td><td>5E14</td></tr><tr><td>110</td><td>2.8E14</td></tr><tr><td>70</td><td>2.5E14</td></tr><tr><td>40</td><td>1.8E14</td></tr><tr><td>20</td><td>1.3E14</td></tr><tr><td colspan="5">Total: 1.34E15</td></tr><tr><td rowspan="4">A17</td><td rowspan="4">N</td><td rowspan="4">400</td><td>190</td><td>1.5E15</td></tr><tr><td>135</td><td>9E14</td></tr><tr><td>90</td><td>9E14</td></tr><tr><td>50</td><td>8E14</td></tr><tr><td>20</td><td>1.3E15</td></tr><tr><td colspan="5">Total: 5.4E15</td></tr></tbody></table>

* Higher implantation energy leads to a deeper generation of $V_{Si}$

* Higher implanted dose leads to a higher concentration of $V_{Si}$

<figure><img src="image_14.png" /><figcaption>After annealing at 900°C for 15min</figcaption></figure>

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

* V1' configuration favored before annealing and V1 configuration favored after annealing at 900°C for 15min.

* Concentration of $V_c V_{Si}$ proportional to the concentration of $V_{Si}$ in V1 configuration after annealing.

* Presence of 6H-SiC inclusions in stacking faults produced during ion implantations (PL5 peak) [6]

* Al implantation decreases the $V_{Si}$ and $V_c V_{Si}$ concentrations

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

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Conclusion

* Implantation of 4H-SiC samples realized

* Simulation of implantations realized to see $V_{Si}$ depth profiles

* Cathodoluminescence measurements are obtained

* Before annealing : $V_{Si}$ concentration maximal for high energy, low dose N-implantation at RT

* After annealing : $V_{Si}$ concentration maximal for high energy, high dose N-implantation at RT and the concentration of $V_c V_{Si}$ is proportional to the concentration of $V_{Si}$

References

[1] She, X et al. *IEEE Trans. Ind. Electron.* **2017**, 64, 8193-8205

[2] Maximilians, J. *PhD thesis*, Universität Würzburg, Germany, **2015**

[3] Castelletto, S et al. *J. Phys. Photonics* **2020**, 2, 022001

[4] Hallén, A et al. *Surf. Coat. Technol.* **2016**, 306, 190-193

[5] Morvan, E. *PhD thesis*, Institut National des Sciences Appliquées de Lyon, France, **1999**

[6] Castelletto, S et al. *Nanomaterials* **2021**, 11, 72

Acknowledgements

Samples have been ion implanted at Pprime Institut (LMP) Potiers, IJCLab (CSNSM) Orsay and IP2I (IPNL) Lyon.

The authors acknowledge the use of resources from the Nanomat platform which is a part of the Renatech platform and is supported by the Ministère de l'Enseignement Supérieur et de la Recherche, the Région Grand Est, and FEDER funds from the European Community