Room-temperature direct bandgap electroluminesence from Ge-on-Si light-emitting diodes
Author(s)Sun, Xiaochen; Liu, Jifeng; Kimerling, Lionel C.; Michel, Jurgen
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We report what we believe to be the first demonstration of direct bandgap electroluminescence (EL) from Ge/Si heterojunction light-emitting diodes (LEDs) at room temperature. In-plane biaxial tensile strain is used to engineer the band structure of Ge to enhance the direct gap luminescence efficiency by increasing the injected electron population in the direct Γ valley. Room-temperature EL is observed at the direct gap energy from a Ge/Si p-i-n diode exhibiting the same characteristics of the direct gap photoluminescence of Ge. The integral direct gap EL intensity increases superlinearly with electrical current owing to an indirect valley filling effect. These results indicate a promising future of tensile-strained Ge-on-Si for electrically pumped, monolithically integrated light emitters on Si.
DepartmentMassachusetts Institute of Technology. Materials Processing Center; Massachusetts Institute of Technology. Department of Materials Science and Engineering; Massachusetts Institute of Technology. Microphotonics Center
Optical Society of America
Xiaochen Sun, Jifeng Liu, Lionel C. Kimerling, and Jurgen Michel, "Room-temperature direct bandgap electroluminesence from Ge-on-Si light-emitting diodes," Opt. Lett. 34, 1198-1200 (2009) http://www.opticsinfobase.org/abstract.cfm?URI=ol-34-8-1198
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