Effects of Annealing on the Behavior of Sn in GeSn Alloy and GeSn-Based Photodetectors

• Published in: IEEE transactions on electron devices 2020-08, Vol.67 (8), p.3229-3234
• Main Authors: Wang, Liming, Zhang, Yichi, Wu, Yifei, Liu, Tao, Miao, Yuanhao, Meng, Lingyao, Jiang, Zuimin, Hu, Huiyong
• Format: Article
• Language: English
• Subjects: Alloys; Annealing; Dark current; Epitaxial growth; Germanium; GeSn alloy; Intermetallic compounds; Lattices; Low temperature; Molecular beam epitaxy; Nanoparticles; photodetection properties; Photodetectors; Photometers; Silicon; Silicon substrates; Sn segregation; Strain; thermal annealing; Tin
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2020.3004123

Ge _{{1}-{x}} Sn x alloy films with Sn contents of 3% and 10% were grown on Si wafers by low-temperature nonequilibrium molecular beam epitaxy. The thermostabilities of the GeSn films and photodetectors containing them were studied. No Sn segregation was observed in Ge 0.97 Sn 0.03 films annealed below 750 °C. Conversely, Sn segregation occurred and Sn nanoparticles formed within the Ge 0.90 Sn 0.10 films annealed above 400 °C. Upon increasing the annealing temperature to 750 °C, Sn particles were thermally driven and segregated on the surface of both Ge 0.97 Sn 0.03 and Ge 0.90 Sn 0.10 films. Photodetectors were fabricated based on the as-grown and annealed Ge 0.90 Sn 0.10 films. Because of the decreased defect content of the Ge 0.90 Sn 0.10 film after annealing, the dark current of the GeSn photodetectors decreased obviously and the responsivity of the devices increased. These results are fundamentally important for the applications of high-performance photodetectors and lasers based on GeSn alloys.