Tensile-strained, n-type Ge as a gain medium for monolithic laser integration on Si

• DOI: 10.1364/oe.15.011272
• Publication Date: 2007-08-31T18:08:46Z
• Authors: Jifeng Liu; Xiaochen Sun; Dong Pan; Xiaoxin Wang; Lionel C. Kimerling; Thomas L. Koch; Jurgen Michel
• Keywords: Population inversion

We analyze the optical gain of tensile-strained, n-type Ge material for Si-compatible laser applications. The band structure unstrained exhibits indirect conduction valleys (L) lower than direct valley (Gamma) by 136 meV. Adequate strain and doping engineering can effectively provide population inversion in bandgap Ge. tensile decreases difference between L Gamma valley, while extrinsic electrons from fill to level compensate remaining energy difference. Our modeling shows that with a combination 0.25% an electron density 7.6x10(19)/cm(3) doping, net ~400 cm(-1) be obtained gap transition despite free carrier absorption loss. threshold current lasing is estimated ~6kA cm(-2) typical edgeemitting double heterojunction structure. These results indicate strained good candidate Si integrated lasers.