Competitiveness between direct and indirect radiative transitions of Ge

Cheng, Tzu-Hurng; Ko, Chih‐Yuan; Chen, C.-Y.; Peng, Kun; Luo, Guang Li; C, Liu; Tseng, Hsing‐Huang

doi:10.1063/1.3352048

Cited by 56 publications

(30 citation statements)

References 11 publications

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“…In order to realize a high efficiency optical emitter that is compatible with standard, Si-based ultra-large-scale integration (ULSI) technology, much effort has been devoted to seek for the possibilities of Si/Ge based light emitting diodes. [1][2][3][4][5][6][7] Besides, the near infrared light source is important for biomedical applications and the compatibility with Si-based micro sensor system is also required. Bulk Si is an indirect band gap material and it is hard to generate radiative recombination unless the momentum conservation is satisfied.…”

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confidence: 99%

Phonon-assisted transient electroluminescence in Si

Cheng

Chu-Su

Liu

et al. 2014

Applied Physics Letters

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The phonon-replica infrared emission is observed at room temperature from indirect band gap Si light-emitting diode under forward bias. With increasing injection current density, the broadened electroluminescence spectrum and band gap reduction are observed due to joule heating. The spectral-resolved temporal response of electroluminescence reveals the competitiveness between single (TO) and dual (TO + TA) phonon-assisted indirect band gap transitions. As compared to infrared emission with TO phonon-replica, the retarder of radiative recombination at long wavelength region (∼1.2 μm) indicates lower transition probability of dual phonon-replica before thermal equivalent.

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confidence: 99%

Phonon-assisted transient electroluminescence in Si

Cheng

Chu-Su

Liu

et al. 2014

Applied Physics Letters

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“…The direct conduction valley of Ge is only 140 meV above the indirect valleys, and the enhancement of direct transition is possible by increasing the electron population in the direct valley. 5 In this letter, the influence of defects on indirect radiative transition of Ge is studied by comparing bulk Ge and Ge grown on Si samples. 3,4 Moreover, the direct transition from the electroluminescence ͑EL͒ of Ge pn junction was also observed.…”

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confidence: 99%

“…2. 5 To avoid the intensity enhancement due to highly doped n-type Ge, 10 both bulk n-type Ge and Ge-on-Si had low dopant concentrations. The PL peaks at 695 meV and 780 meV are attributed to the indirect band transition and direct band transition, respectively.…”

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confidence: 99%

Influence of defects and interface on radiative transition of Ge

Jan

Chen

Lee

et al. 2011

Applied Physics Letters

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The influences of defects and surface roughness on the indirect bandgap radiative transition of Ge were studied. Bulk Ge has 15 times the integrated intensity of photoluminescence of Ge-on-Si. However, for Ge-on-Si sample, the direct transition related photoluminescence intensity is higher than the indirect transition related one. We affirm that the defects in the Ge-on-Si are responsible for the weak indirect transition and relatively strong direct transition. The scattering of electrons by roughness at Ge/oxide interface can provide extra momentum of the indirect band transition of Ge, and thus enhance the indirect radiative transition.

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“…An additional approach to the spectroscopy of the E 0 transition in Ge-rich materials is room temperature photoluminescence (PL). [19][20][21][22][23][24] Emission from E 0 is very weak in bulk Ge crystals due to reabsorption, [25][26][27] but becomes the strongest feature in micron-thick films. Accordingly, we now extend these studies to Ge 1-x Si x alloys, where the increasing separation between E 0 and the lowest indirect transitions should lead to a weakening of the E 0 signal, a trend that is confirmed by our experimental data.…”

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confidence: 99%

Optical properties of Ge-richGe1−xSixalloys: Compositional dependence of the lowest direct and indirect gaps

Gallagher

Senaratne

et al. 2016

Phys. Rev. B

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Ge-rich Ge 1-x Si x alloys have been investigated using spectroscopic ellipsometry and photoluminescence at room temperature. Special emphasis was placed on the compositional dependence of the lowest-energy interband transitions. For x ≤ 0.05, a compositional range of particular interest for modern applications, we find E 0 = 0.799(1)+3.214(45)x+0.080(44)x 2 (in eV) for the lowest direct gap. The compositional dependence of the indirect gap is obtained from photoluminescence as E ind = 0.659(4)+1.18(17)x (in eV). We find no significant discrepancies between these results and extrapolations from measurements at higher Si concentrations. Such discrepancies had been suggested by recent work on Ge 1-x Si x films on Si. An accurate knowledge of the interband transition energies is an important requirement for the design of devices incorporating Ge-rich Ge 1-x Si x alloys and for the understanding of more complex systems, such as ternary Ge 1-x-y Si x Sn y alloys, in terms of its binary constituents.

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Competitiveness between direct and indirect radiative transitions of Ge

Cited by 56 publications

References 11 publications

Phonon-assisted transient electroluminescence in Si

Phonon-assisted transient electroluminescence in Si

Influence of defects and interface on radiative transition of Ge

Optical properties of Ge-richGe1−xSixalloys: Compositional dependence of the lowest direct and indirect gaps

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