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Title: Improved thin film quality and photoluminescence of N-doped epitaxial germanium-on-silicon using MOCVD
Authors: Zhou, Guangnan
Covian, Alejandra V. Cuervo
Lee, Kwang Hong
Han, Han
Tan, Chuan Seng
Liu, Jifeng
Xia, Maggie Guangrui
Keywords: Engineering::Electrical and electronic engineering::Semiconductors
Issue Date: 2019
Source: Zhou, G., Covian, A. V. C., Lee, K. H., Han, H., Tan, C. S., Liu, J., & Xia, M. G. (2020). Improved thin film quality and photoluminescence of N-doped epitaxial germanium-on-silicon using MOCVD. Optical Materials Express, 10(1), 1-13. doi:10.1364/OME.10.000001
Project: NRF-CRP19-2017-01-00
Journal: Optical Materials Express
Abstract: This paper addresses one of the key issues in the scientific community of Si photonics: thin-film quality and the light emission properties of band-engineered n+ Germanium-on-Silicon (Ge-on-Si). Compared to the traditional delta doping approach, which was utilized in the first electrically-pumped Ge-on-Si lasers, we offer an n+ Ge-on-Si thin film with better material quality and higher carrier injection efficiency grown by metal-organic chemical vapor deposition (MOCVD). The impacts of thermal cycle annealing and Si substrate offcut on the thin film quality were investigated, including surface roughness, strain, threading dislocation density, Si-Ge interdiffusion, and dopant diffusion. It was revealed that: 1) MOCVD overcomes the outdiffision issue of n-type dopants by having the dopant peaks at the bottom of the Ge films; 2) the characterization of the light emission properties of these MOCVD n+ Ge-on-Si samples (1.0 × 1019 cm−3 doped) compared to delta-doped ultra-high vacuum chemical vapor deposition (UHVCVD) Ge, showing comparable photoluminescence (PL) spectral intensity at 1/4 of the doping level; 3) Detailed PL spectral analyses showed that population inversion from the direct gap transition has been achieved, and the injected electron density in the direct Γ valley is comparable to that of the delta-doped sample even though the n-type doping level is 75% less; and 4) Experimental evidences that Si-Ge interdiffusion has a much larger impact on PL intensity than threading dislocation density in the range of 108-109/cm3. These results indicate that MOCVD n+ Ge is very promising to reduce the threshold of Ge gain media on Si notably.
ISSN: 2159-3930
DOI: 10.1364/OME.10.000001
Rights: © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.
Fulltext Permission: open
Fulltext Availability: With Fulltext
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