Non-radiative recombination in Ge1− y Sn y light emitting diodes: The role of strain relaxation in tuned heterostructure designs

• Published in: Journal of applied physics 2015-06, Vol.117 (24)
• Main Authors: Gallagher, J. D., Senaratne, C. L., Xu, C., Sims, P., Aoki, T., Smith, D. J., Menéndez, J., Kouvetakis, J.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4923060

This paper describes the properties of Ge1−ySny light emitting diodes with a broad range of Sn concentrations (y = 0.0–0.11). The devices are grown upon Si(100) platforms using ultra-low temperature deposition of highly reactive Ge and Sn hydrides. The device fabrication adopts two new photodiode designs which lead to optimized performance and enables a systematic study of the effects of strain relaxation on emission efficiency. In contrast with n-Ge/i-Ge1−ySny/p-Ge analogs, which in most cases contain two defected interfaces, our designs include a p-layer with composition Ge1−zSnz chosen to be z  0.09, for which it is practically impossible to avoid strain relaxation in n-Ge/i-Ge1−ySny/p-Ge analogs. The new designs introduced here open the door to the fabrication of highly efficient electrically pumped systems for applications in future generations of integrated photonics.