Analysis of enhanced light emission from highly strained germanium microbridges

作者：Sueess, M. J.; Geiger, R.; Minamisawa, R. A.; Schiefler, G.; Frigerio, J.; Chrastina, D.; Isella, G.; Spolenak, R.; Faist, J.; Sigg, H.^*

来源：Nature Photonics, 2013, 7(6): 466-472.

DOI：10.1038/NPHOTON.2013.67

• SILICON
• LASER
• GE
• SI
• INTERCONNECTS
• INTEGRATION
• PHOTONICS

Tensile strain is a widely discussed means for inducing a direct bandgap in Ge for the realization of a semiconductor laser compatible with Si microelectronics. We present a top-down fabrication approach for creating high uniaxial tensile stress in suspended Ge structures, which enhances-by a factor of more than 20-the strain induced by thermal mismatch of Ge layers grown on silicon or silicon-on-insulator substrates. Strain values up to 3.1% are measured using Raman spectroscopy, in excellent agreement with simulations using a biaxial thermal strain of 0.15%. As expected from the high value of strain, a 210 meV peak energy shift in the emission with respect to bulk Ge and a strong increase (325) in the integrated photoluminescence intensity are observed. Although 3.1% uniaxial strain does not transform Ge into a direct-gap material, our model calculation predicts an optical gain of 460 cm(-1) for 1 x 10(19) cm(-3) n-doped structures at an electron-hole injection density of 3 x 10(19) cm(-3).

• 出版日期2013-6