1. Highly reflective and passivated ohmic contacts in p-Ge by laser processing of aSiCx:H(i)/Al2O3/aSiC films for thermophotovoltaic applications
- Author
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Universitat Politècnica de Catalunya. Doctorat en Enginyeria Electrònica, Universitat Politècnica de Catalunya. Departament d’Enginyeria Gràfica i de Disseny, Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya. MNT-Solar - Grup de Micro i Nano Tecnologies per Energia Solar, Gamel, Mansur Mohammed Ali, López Rodríguez, Gema, Medrano Gómez, Álvaro Manuel, Jiménez Rodríguez, Alba María, Datas Medina, Alejandro, Garin Escriva, Moises, Martín García, Isidro, Universitat Politècnica de Catalunya. Doctorat en Enginyeria Electrònica, Universitat Politècnica de Catalunya. Departament d’Enginyeria Gràfica i de Disseny, Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya. MNT-Solar - Grup de Micro i Nano Tecnologies per Energia Solar, Gamel, Mansur Mohammed Ali, López Rodríguez, Gema, Medrano Gómez, Álvaro Manuel, Jiménez Rodríguez, Alba María, Datas Medina, Alejandro, Garin Escriva, Moises, and Martín García, Isidro
- Abstract
Crystalline germanium (c-Ge) has historically been regarded as a cost-effective alternative to III-V semiconductors for thermophotovoltaic (TPV) device fabrication. However, Ge-based devices have not yet reported high efficiencies, partially due to the lack of an efficient back-surface reflector that turns back to the heat source out-band (sub-bandgap) thermal radiation. The difficulty of implementing back surface reflectors in Ge TPV cells is related to the simultaneous requirement of good back surface passivation, low electrical resistivity, and high out-band optical reflectivity. In this study, we demonstrate a highly reflective ohmic contact to p-type c-Ge (doping concentration of 2 × 1015 cm-3) made of an aSiCx(1 nm)/Al2O3 (50 nm)/aSiC (45 nm) stack that is laser processed using Nd:YVO4 laser emitting at 355 nm to create punctual p+ contacts (locally diffused Al regions). This stack is finally caped with a thick (1000 nm) Al layer that behaves as a metallic mirror and back electrode. As the laser processed area increases from 0.1 to 3 %, which is the typical range in the final devices, the surface recombination velocity increase from 10.5 to 60.0 cm/s, while the effective contact resistance reduces from 0.462 to 0.036 O cm2. Moreover, a sub-bandgap reflectance of 90–98 % is achieved. Simulations assuming ideal device configuration indicate that implementing these back contacts could potentially enable TPV cell conversion efficiencies comparable to the reported high-efficiency c-Ge TPV cells operating at similar illumination temperature., Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant, Postprint (published version)
- Published
- 2024