Simple Electroabsorption Calculator for Designing 1310 nm and 1550 nm Modulators Using Germanium Quantum Wells

Schaevitz, Rebecca K.; Edwards, Elizabeth H.; Roth, Jonathan E.; Fei, E. T.; Rong, Yaoguang; Wahl, Pierre; Kamins, Theodore I.; Harris, James S.; Miller, David A. B.

doi:10.1109/jqe.2011.2170961

Cited by 35 publications

(47 citation statements)

References 32 publications

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“…The first is that the exciton enhanced direct transitions appear to have a ∼15% reduction in peak height from the theoretically predicted value given by SQWEAC. 22 The theoretically predicted value is based on the nominal 10 nm QWs 22 in contrast to the ∼14 nm well widths simulated here. The wider well widths likely have a reduction in the excitonic enhancements than is predicted by the model (as previously discussed 22 ).…”

Section: Resultsmentioning

confidence: 84%

“…We use the model-solid theory presented by Van de Walle and Martin 23,24 to calculate the indirect band gaps and band alignments of Ge/SiGe QWs on a tensile strained VS. 22 The effectiveness of this method was verified by Busby, et al, for calculating the band alignments of the direct, L and -valleys in a Ge/Si 0.2 Ge 0.8 quantum well system grown on a graded Si 0.15 Ge 0.85 relaxed substrate. 25 For ease of later discussion, we will reprint the equations and constants used to calculate the band gaps and band offsets.…”

Section: A Band Structurementioning

confidence: 94%

“…Simulation of QCSE is a combination of the tunneling resonance method for the quantum-confined levels structure, a 2D Sommerfeld model for excitonic enhancement of the above band gap absorption, and a variational method on an effective 1S exciton for excitonic effects below the bandgap. This model, which we call the Simple Quantum Well Electroabsorption calculator, or SQWEAC, 22 fully simulates the QCSE portion of the electroabsorption spectra in Ge/SiGe quantum wells. The detail of the QCSE portion of SQWEAC is published elsewhere.…”

Section: Theorymentioning

confidence: 99%

“…The detail of the QCSE portion of SQWEAC is published elsewhere. 22 In this section, we will specifically discuss the modeling of the indirect absorption used in that SQWEAC. To model the indirect absorption in Ge/SiGe quantum wells, we need to understand the overall band structure (specifically the band gaps and potentially any type-I confinement), the type of phonons present and the temperature of measurement.…”

Section: Theorymentioning

confidence: 99%

“…To calculate the two transitions from conduction to LH and HH, the splitting energies of the LH and HH as deduced by QCSE spectra (simulated in SQWEAC) are added to the relevant band gap. 22,33 The indirect masses associated with the conduction bands are calculated according to the model presented by Rieger, 34 while the LH and HH masses are calculated in the same way as presented in the SQWEAC model. 22,33 …”

Section: A Band Structurementioning

confidence: 99%

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Indirect absorption in germanium quantum wells

et al. 2011

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Germanium has become a promising material for creating CMOS-compatible optoelectronic devices, such as modulators and detectors employing the Franz-Keldysh effect (FKE) or the quantum-confined Stark effect (QCSE), which meet strict energy and density requirements for future interconnects. To improve Ge-based modulator design, it is important to understand the contributions to the insertion loss (IL). With indirect absorption being the primary component of IL, we have experimentally determined the strength of this loss and compared it with theoretical models. For the first time, we have used the more sensitive photocurrent measurements for determining the effective absorption coefficient in our Ge/SiGe quantum well material employing QCSE. This measurement technique enables measurement of the absorption coefficient over four orders of magnitude. We find good agreement between our thin Ge quantum wells and the bulk material parameters and theoretical models. Similar to bulk Ge, we find that the 27.7 meV LA phonon is dominant in these quantum confined structures and that the electroabsorption profile can be predicted using the model presented by Frova, Phys. Rev., 145 (1966)

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Section: Resultsmentioning

confidence: 84%