Theoretical study of the optical gain characteristics of a Ge sub(1-x)Sn sub(x) alloy for a short-wave infrared laser

• Published in: Chinese physics B Vol. 24; no. 2; pp. 024211 - 1-024211-7
• Main Authors: Zhang, Dong-Liang, Cheng, Bu-Wen, Xue, Chun-Lai, Zhang, Xu, Cong, Hui, Liu, Zhi, Zhang, Guang-Ze, Wang, Qi-Ming
• Format: Journal Article
• Language: English
• Published: 01.02.2015
• Subjects: Carrier density; Density; Diodes; Gain; Infrared; Infrared lasers; Lasers; Simulation; Threshold currents
• ISSN: 1674-1056; 1741-4199
• DOI: 10.1088/1674-1056/24/2/024211

Optical gain characteristics of Ge sub(1-x)Sn sub(x) are simulated systematically. With an injection carrier concentration of 5 x 10 super(18)/cm super(3) at room temperature, the maximal optical gain of Ge sub(0.922)Sn sub(0.078) alloy (with n-type doping concentration being 5 x 10 super(18)/cm super(3)) reaches 500 cm super(-1). Moreover, considering the free-carrier absorption effect, we find that there is an optimal injection carrier density to achieve a maximal net optical gain. A double heterostructure Ge sub(0.554)Si sub(0.289)Sn sub(0.157)/Ge sub(0.922)Sn sub(0 .078)/Ge sub(0.554)Si sub(0.289)Sn sub(0.157) short-wave infrared laser diode is designed to achieve a high injection efficiency and low threshold current density. The simulation values of the device threshold current density are 6.47 kA/cm super(2) (temperature: 200 K, and [lambda] = 2050 nm). 10.75 kA/cm super(2) (temperature: 200 K, and [lambda] = 2000 nm), and 23.12 kA/cm super(2) (temperature: 300 K, and [lambda] = 2100 nm), respectively. The results indicate the possibility to obtain a Si-based short-wave infrared Ge sub(1-x)Sn sub(x) laser.