Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics
This study investigated the low contact resistivity and Schottky barrier characteristics in p-GaN by modifying the thickness and doping levels of a p-InGaN cap layer. A comparative analysis with highly doped p-InGaN revealed the key mechanisms contributing to low-resistance contacts. Atomic force mi...
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2025-01-01
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| author | Mohit Kumar Laurent Xu Timothée Labau Jérôme Biscarrat Simona Torrengo Matthew Charles Christophe Lecouvey Aurélien Olivier Joelle Zgheib René Escoffier Julien Buckley |
| author_facet | Mohit Kumar Laurent Xu Timothée Labau Jérôme Biscarrat Simona Torrengo Matthew Charles Christophe Lecouvey Aurélien Olivier Joelle Zgheib René Escoffier Julien Buckley |
| author_sort | Mohit Kumar |
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| description | This study investigated the low contact resistivity and Schottky barrier characteristics in p-GaN by modifying the thickness and doping levels of a p-InGaN cap layer. A comparative analysis with highly doped p-InGaN revealed the key mechanisms contributing to low-resistance contacts. Atomic force microscopy inspections showed that the surface roughness depends on the doping levels and cap layer thickness, with higher doping improving the surface quality. Notably, increasing the doping concentration in the p<sup>++</sup>-InGaN cap layer significantly reduced the specific contact resistivity to 6.4 ± 0.8 × 10<sup>−6</sup> Ω·cm<sup>2</sup>, primarily through enhanced tunneling. Current–voltage (I–V) characteristics indicated that the cap layer’s surface properties and strain-induced polarization effects influenced the Schottky barrier height and reverse current. The reduction in barrier height by approximately 0.42 eV in the p<sup>++</sup>-InGaN layer enhanced hole tunneling, further lowering the contact resistivity. Additionally, polarization-induced free charges at the metal–semiconductor interface reduced band bending, thereby enhancing carrier transport. A transition in current conduction mechanisms was also observed, shifting from recombination tunneling to space-charge-limited conduction across different voltage ranges. This research underscores the importance of doping, cap layer thickness, and polarization effects in achieving ultra-low contact resistivity, offering valuable insights for improving the performance of p-GaN-based power devices. |
| format | Article |
| id | doaj-art-0d3b57e52abb48c58e8a1dc1465ebb83 |
| institution | Kabale University |
| issn | 2073-4352 |
| language | English |
| publishDate | 2025-01-01 |
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| series | Crystals |
| spelling | doaj-art-0d3b57e52abb48c58e8a1dc1465ebb832025-01-24T13:28:09ZengMDPI AGCrystals2073-43522025-01-011515610.3390/cryst15010056Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height CharacteristicsMohit Kumar0Laurent Xu1Timothée Labau2Jérôme Biscarrat3Simona Torrengo4Matthew Charles5Christophe Lecouvey6Aurélien Olivier7Joelle Zgheib8René Escoffier9Julien Buckley10CEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceCEA, Leti, Université Grenoble Alpes, 38000 Grenoble, FranceThis study investigated the low contact resistivity and Schottky barrier characteristics in p-GaN by modifying the thickness and doping levels of a p-InGaN cap layer. A comparative analysis with highly doped p-InGaN revealed the key mechanisms contributing to low-resistance contacts. Atomic force microscopy inspections showed that the surface roughness depends on the doping levels and cap layer thickness, with higher doping improving the surface quality. Notably, increasing the doping concentration in the p<sup>++</sup>-InGaN cap layer significantly reduced the specific contact resistivity to 6.4 ± 0.8 × 10<sup>−6</sup> Ω·cm<sup>2</sup>, primarily through enhanced tunneling. Current–voltage (I–V) characteristics indicated that the cap layer’s surface properties and strain-induced polarization effects influenced the Schottky barrier height and reverse current. The reduction in barrier height by approximately 0.42 eV in the p<sup>++</sup>-InGaN layer enhanced hole tunneling, further lowering the contact resistivity. Additionally, polarization-induced free charges at the metal–semiconductor interface reduced band bending, thereby enhancing carrier transport. A transition in current conduction mechanisms was also observed, shifting from recombination tunneling to space-charge-limited conduction across different voltage ranges. This research underscores the importance of doping, cap layer thickness, and polarization effects in achieving ultra-low contact resistivity, offering valuable insights for improving the performance of p-GaN-based power devices.https://www.mdpi.com/2073-4352/15/1/56p<sup>++</sup>-InGaNcontact resistivitySchottky barrier heightpolarization effectscarrier transport mechanismGaN-based heterostructures |
| spellingShingle | Mohit Kumar Laurent Xu Timothée Labau Jérôme Biscarrat Simona Torrengo Matthew Charles Christophe Lecouvey Aurélien Olivier Joelle Zgheib René Escoffier Julien Buckley Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics Crystals p<sup>++</sup>-InGaN contact resistivity Schottky barrier height polarization effects carrier transport mechanism GaN-based heterostructures |
| title | Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics |
| title_full | Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics |
| title_fullStr | Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics |
| title_full_unstemmed | Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics |
| title_short | Effect of p-InGaN Cap Layer on Low-Resistance Contact to p-GaN: Carrier Transport Mechanism and Barrier Height Characteristics |
| title_sort | effect of p ingan cap layer on low resistance contact to p gan carrier transport mechanism and barrier height characteristics |
| topic | p<sup>++</sup>-InGaN contact resistivity Schottky barrier height polarization effects carrier transport mechanism GaN-based heterostructures |
| url | https://www.mdpi.com/2073-4352/15/1/56 |
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