Band-engineered Ge-on-Si lasers

Liu, Jifeng; Sun, Xiaochen; Camacho-Aguilera, Rodolfo; Cai, Yan; Michel, Jürgen; Kimerling, Lionel C.

doi:10.1109/iedm.2010.5703311

Cited by 8 publications

(4 citation statements)

References 8 publications

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“…The estimate of efficiency enhancement by n-type doping is consistent with previous PL studies (Sun et al 2009b). Liu et al (2010b) further performed electrical injection modeling for n + Ge with a doping level of 5 × 10 19 cm −3 , which can potentially achieve a net material gain of >200 cm −1 . Figure 9 shows a simulation result of band diagrams, quasi-Fermi levels and carrier concentration distribution in an n + Si/n + Ge/p + Si DH structure upon electrical injection.…”

Section: Electrically Pumped Ge-on-si Laserssupporting

confidence: 87%

Monolithic Ge-on-Si lasers for large-scale electronic–photonic integration

Liu

Kimerling

Michel

2012

Semicond. Sci. Technol.

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114

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A silicon-based monolithic laser source has long been envisioned as a key enabling component for large-scale electronic-photonic integration in future generations of high-performance computation and communication systems. In this paper we present a comprehensive review on the development of monolithic Ge-on-Si lasers for this application. Starting with a historical review of light emission from the direct gap transition of Ge dating back to the 1960s, we focus on the rapid progress in band-engineered Ge-on-Si lasers in the past five years after a nearly 30-year gap in this research field. Ge has become an interesting candidate for active devices in Si photonics in the past decade due to its pseudo-direct gap behavior and compatibility with Si complementary metal oxide semiconductor (CMOS) processing. In 2007, we proposed combing tensile strain with n-type doping to compensate the energy difference between the direct and indirect band gap of Ge, thereby achieving net optical gain for CMOS-compatible diode lasers. Here we systematically present theoretical modeling, material growth methods, spontaneous emission, optical gain, and lasing under optical and electrical pumping from band-engineered Ge-on-Si, culminated by recently demonstrated electrically pumped Ge-on-Si lasers with >1 mW output in the communication wavelength window of 1500-1700 nm. The broad gain spectrum enables on-chip wavelength division multiplexing. A unique feature of band-engineered pseudo-direct gap Ge light emitters is that the emission intensity increases with temperature, exactly opposite to conventional direct gap semiconductor light-emitting devices. This extraordinary thermal anti-quenching behavior greatly facilitates monolithic integration on Si microchips where temperatures can reach up to 80 • C during operation. The same band-engineering approach can be extended to other pseudo-direct gap semiconductors, allowing us to achieve efficient light emission at wavelengths previously considered inaccessible.

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Section: Electrically Pumped Ge-on-si Laserssupporting

confidence: 87%

Monolithic Ge-on-Si lasers for large-scale electronic–photonic integration

Liu

Kimerling

Michel

2012

Semicond. Sci. Technol.

Self Cite

114

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“…Fortunately, tensile strain engineering and Sn-alloying engineering have enabled Ge to become a quasi-direct bandgap or direct bandgap material due to the small bandgap difference between its two minima in conduction bands (only 136 meV). Experimental research has shown an optical gain of 0.24% for tensile-strained n + -type Ge (the n-type doping level is 1 × 10 19 cm −3 ), which led to the creation of optically injected and electrically injected Ge lasers [ 29 , 30 , 31 , 32 ]. However, the threshold for a Ge laser is too high, which means that weak tensile-strained n + -type Ge is not able to supply enough optical gain to achieve low-threshold lasing.…”

Section: Introductionmentioning

confidence: 99%

Review of Si-Based GeSn CVD Growth and Optoelectronic Applications

et al. 2021

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GeSn alloys have already attracted extensive attention due to their excellent properties and wide-ranging electronic and optoelectronic applications. Both theoretical and experimental results have shown that direct bandgap GeSn alloys are preferable for Si-based, high-efficiency light source applications. For the abovementioned purposes, molecular beam epitaxy (MBE), physical vapour deposition (PVD), and chemical vapor deposition (CVD) technologies have been extensively explored to grow high-quality GeSn alloys. However, CVD is the dominant growth method in the industry, and it is therefore more easily transferred. This review is focused on the recent progress in GeSn CVD growth (including ion implantation, in situ doping technology, and ohmic contacts), GeSn detectors, GeSn lasers, and GeSn transistors. These review results will provide huge advancements for the research and development of high-performance electronic and optoelectronic devices.

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“…Although Ge is an indirect-band-gap semiconductor like Si, the energy difference between its direct and indirect band gaps is much smaller than Si and it has been shown that introduction of tensile strain (4,5) and heavily n-type doping can reduce this difference and significantly enhance the direct-gap light emission (6)(7)(8). On the basis of these methods, optical gain (9) and optically and electrically pumped lasers (10)(11)(12)(13)(14) have been demonstrated, whereas threshold currents were not sufficiently low for practical device applications. Further increase in the doping concentration and improvements of crystallinity are considered to be required for reduction of the threshold current.…”

Section: Introductionmentioning

confidence: 99%

Strong Room-Temperature Electroluminescence from Ge-on-Si by Precise in-situ Doping Control

2020

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We observe strong room-temperature electroluminescence from Ge-on-Si. Ge p-i-n junction is formed within the epitaxial Ge by the precise in-situ doping method and additionally high density P delta doping is performed in the vicinity of the surface to create a low resistivity Ohmic contact. An EL device was mesa-defined by the photo-lithography and following reactive ion etching process in order to suppress leak current. Current-voltage characteristic reveal a good diode rectifying property with an on/off ratio of over 105. The EL spectrum appears at around 2.1 kA/cm2 injected current, and the EL intensity drastically increases with the injection current increase. These results indicate that the Ge-on-Si p-i-n structure has high potential to realize high efficiency Ge lasers monolithically integrated on the Si platform.

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Band-engineered Ge-on-Si lasers

Cited by 8 publications

References 8 publications

Monolithic Ge-on-Si lasers for large-scale electronic–photonic integration

Monolithic Ge-on-Si lasers for large-scale electronic–photonic integration

Review of Si-Based GeSn CVD Growth and Optoelectronic Applications

Strong Room-Temperature Electroluminescence from Ge-on-Si by Precise in-situ Doping Control

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