Direct-Gap Gain and Optical Absorption in Germanium Correlated to the Density of Photoexcited Carriers, Doping, and Strain

作者：Carroll Lee^*; Friedli Peter; Neuenschwander Stefan; Sigg Hans; Cecchi Stefano; Isa Fabio; Chrastina Daniel; Isella Giovanni; Fedoryshyn Yuriy; Faist Jerome

来源：Physical Review Letters, 2012, 109(5): 057402.

DOI：10.1103/PhysRevLett.109.057402

Direct-gap gain up to 850 cm(-1) at 0.74 eV is measured and modeled in optically pumped Ge-on-Si layers for photoexcited carrier densities of 2.0 x 10(20) cm(-3). The gain spectra are correlated to carrier density via plasma-frequency determinations from reflection spectra. Despite significant gain, optical amplification cannot take place, because the carriers also generate pump-induced absorption of approximate to 7000 cm(-1). Parallel studies of III-V direct-gap InGaAs layers validate our spectroscopy and modeling. Our self-consistent results contradict current explanations of lasing in Ge-on-Si cavities.

• 出版日期2012-8-1