• Reboud, Vincent
• Alba, Pablo Acosta
• Casiez, Lara
• Rouchon, Denis
• Chrétien, Jérémie
• Calvo, Vincent
• Hartmann, J. M.
• Pauc, N.
• Richy, Jérôme
• Frauenrath, Marvin
• Bernier, N.
• Chelnokov
• Bertrand, M.
• Mazen, F.

Abstract

<jats:p> We investigate the recrystallization of thick phosphorus-implanted GeSn layers using 308 nm Ultraviolet Nanosecond Laser Annealing (UV-NLA). We identify the optimal annealing conditions leading to the reconstruction of Ge<jats:sub>0.92</jats:sub>Sn<jats:sub>0.08</jats:sub> crystal amorphized by dopant implantation. The fully recrystallized GeSn layers present specific structures with localized tin and strain variations. Above the non-amorphized and unmelted Ge<jats:sub>0.92</jats:sub>Sn<jats:sub>0.08</jats:sub> seed layer, a first highly tensile strained GeSn sublayer is formed, with a tin gradient from 2.5% up to 10.5%. Closer to the surface, a second sublayer consists of tin-enriched vertical structures in a Ge<jats:sub>0.93</jats:sub>Sn<jats:sub>0.07</jats:sub> matrix. Laser annealing enables us to reverse the strain of the GeSn layer. The initial GeSn presents a compressive strain of −0.10%, while the recrystallized Ge<jats:sub>0.93</jats:sub>Sn<jats:sub>0.07</jats:sub> matrix is tensile strained at 0.39%. UV-NLA presents the advantages of (i) local annealing that recrystallizes amorphized GeSn layers after implantation without excessive tin segregation and (ii) reversing the strain of epitaxial GeSn layers from compressive to tensile. Our results open up promising perspectives for the integration of GeSn mid-IR photonic devices. </jats:p>

Topics

• impedance spectroscopy
• surface
• annealing
• tin
• recrystallization
• Phosphorus