Epitaxial Growth of Germanium on Silicon for Light Emitters

Chengzhao Chen,Shihao Huang,Cheng Li,Hongkai Lai,Songyan Chen,Yuanyu Zheng

doi:10.1155/2012/768605

Chengzhao Chen, Shihao Huang + Show 4 more

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https://doi.org/10.1155/2012/768605

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Abstract

This paper describes the role of Ge as an enabler for light emitters on a Si platform. In spite of the large lattice mismatch of ~4.2% between Ge and Si, high-quality Ge layers can be epitaxially grown on Si by ultrahigh-vacuum chemical vapor deposition. Applications of the Ge layers to near-infrared light emitters with various structures are reviewed, including the tensile-strained Ge epilayer, the Ge epilayer with a delta-doping SiGe layer, and the Ge/SiGe multiple quantum wells on Si. The fundamentals of photoluminescence physics in the different Ge structures are discussed briefly.

Highlights

In the past decades, the zeal for investigating germanium has been stimulated by its novel application in electronic and optoelectronic devices
This paper describes the role of Ge as an enabler for light emitters on a Si platform
The central issue in obtaining useful Ge films on Si is overcoming the negative effects of the difference in thermal expansion coefficient and the large lattice mismatch (4.2% at 300 K) between these two materials, which cause (i) a high density of misfit dislocations at the interface and a high threading dislocation density (TDD) in the Ge layers, which severely affects the performance of Ge devices because of the recombination centres that are introduced along these dislocations, and (ii) high surface roughness due to island growth, making subsequent device processing very difficult because complementary metal-oxide-semiconductor (CMOS) devices require planar processing

Summary

Introduction

The zeal for investigating germanium has been stimulated by its novel application in electronic and optoelectronic devices. Light-emitting diodes using Ge pin structures on Si have been demonstrated and the first optically pumped Ge-on-Si laser operating at room temperature was fabricated [15, 16] Due to their small lattice mismatch with GaAs (aGe = 0.565785 nm, aGaAs = 0.56533 nm) and similar thermal expansion coefficients, Ge layers can be used as templates for the growth of GaAs-based heterostructures such as diodes and solar cells [17], laser diodes [18], high electron mobility and heterojunction bipolar transistors [19, 20]. Shown that obtaining low TDD and a smooth surface layer at the same time is still very problematic

Epitaxial Growth of Ge on Si with Low Dislocation Density

Ge on Si for Light Emitters

Findings

Conclusion