1 / 10

Ge-on-Si laser operation at room temperaure

Ge-on-Si laser operation at room temperaure. High Speed Circuits & Systems Laboratory Joungwook Moon 2011. 4. Contents. Abstract 1. Introduction 2. Material and Device Structure 3. Emission Characteristics 4. Summary. Abstract.

zlhna
Télécharger la présentation

Ge-on-Si laser operation at room temperaure

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ge-on-Si laser operation at room temperaure High Speed Circuits & Systems Laboratory Joungwook Moon 2011. 4.

  2. Contents • Abstract • 1. Introduction • 2. Material and Device Structure • 3. Emission Characteristics • 4. Summary

  3. Abstract • First experimental observation of lasing from the direct gap transition of Ge-on-Si at room temperature using an edge-emitting waveguide device. • The emission exhibited a gain spectrum of 1590-1610nm, Predominantly TE with increasing gain, and a clear threshold behavior.

  4. 1. Introduction • monolithically integrated lasers on Si have been one of the biggest challenges (SiGe nanostructures, Er doped Si. GeSn β-FeSi2, and Hybrid Ⅲ-Ⅴ lasers on Si ) • Ge, indirect-gap meterial, can be band engineered to behave like a direct-gap material by using tensile strain and n-type doping

  5. 2. Material and Device Structure(1) • Energy band engineering of Ge • Why engineering Ge band structure? •  Reduce band gap difference between Direct & Indirect. • Provide population inversion in the direct bandgap Direct Indirect 136 eV

  6. 2. Material and Device Structure(2) • Direct Band gap PL(Photoluminescence) of tensile-strained, n-type Ge-on-Si at room temperature • Ge waveguides were selectively grown epitaxially on Siby UHVCVD. • (Ultra high vacuum chemical vapor deposition) • Ge Growth temp. 650’C , 0.24% thermally-induced tensile strain was accumlated.  shrinks the direct gap of GE to 0.76 eV • Ge was In-situ doped with 1X1019 cm-3 phosphorous during the growth •  Futher compensate the energy difference between direct • and significantly enhance the direct gap light emission

  7. 2. Material and Device Structure(3) • A cross sectional SEM picture & Setup procesure • Ge waveguide Width = 1.6 um / Length=4.8mm / Hight = 500nm • Both edges were mirror polished to obtain vertical facets for reflection mirrors • (mirror loss << 10 cm-1 , much smaller than optical gain of Ge) • 1064nm Q-Switched laser with pulse duration of 1.5ns excited the entire waveguide • The pump laser was focused into a line by a cylindrical lens, and vertically incident on top of a Ge waveguide • The pulsed edge emission is collected into monochromator, and detected by an InGaAs photomultiplier

  8. 3. Emission Characteristics(1) • The threshold pumping energy is ~5uJ • Increase of carrier inection  Gain specturm shifts to shorter wavelengths • (occupation of higher energy stats in the direct Γ valley) ( k ∝ 1/λ ) laser emission threshold (a) Spontaneous emission

  9. 3. Emission Characteristics(2) • Periodic peaks corresponding to longitudinal Fabry-Perot modes are clearly observed. • Δλ = 0.060±0.003 nm @cavity length 4.8 mm. (b)

  10. 4. Summary • Demonstrated an optically pumped edge-emitting multimode Ge-on-Si laser operating at room temperature with a gain spectrum of 1590-1610 nm.

More Related