Experimental observation of type-I energy band alignment in lattice-matched Ge1−x−ySixSny/Ge heterostructures

Yamaha, Takashi; Shibayama, Shigehisa; Asano, Tanemasa; Kato, Kimihiko; Sakashita, Mitsuo; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

doi:10.1063/1.4941991

Cited by 28 publications

(15 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, if we reduce the Si concentration to 39% in order to match the measured strain exactly, we predict a valence band offset of 0.13 eV, in even better agreement with the measurements in Ref. 42. This level of agreement can be considered very satisfactory given the sensitivity to the compositions and the fact that the band offsets were extracted by approximating the valence band density of states as a linear function of energy near the band edge, rather than by trying to model it using realistic expressions.…”

Section: Discussionsupporting

confidence: 69%

“…34 These results provide strong support for Li's theoretical results. Accordingly, we use for a Ge 1-x-y Si x Sn y alloy 42 For a Ge/Ge 0.44 Si 0.41 Sn 0.15 alloy, the valence band offset was found to be 0.11 eV (higher on the Ge side), which should be compared with 0.15 eV predicted in a calculation of the heterostructure using Eq. (4) for E v,av (x,y).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Direct gap Ge1-ySny alloys: Fabrication and design of mid-IR photodiodes

Senaratne

Wallace

Gallagher

et al. 2016

Journal of Applied Physics

View full text Add to dashboard Cite

Chemical vapor deposition methods were developed, using stoichiometric reactions of specialty Ge3H8 and SnD4 hydrides, to fabricate Ge1-ySny photodiodes with very high Sn concentrations in the 12%–16% range. A unique aspect of this approach is the compatible reactivity of the compounds at ultra-low temperatures, allowing efficient control and systematic tuning of the alloy composition beyond the direct gap threshold. This crucial property allows the formation of thick supersaturated layers with device-quality material properties. Diodes with composition up to 14% Sn were initially produced on Ge-buffered Si(100) featuring previously optimized n-Ge/i-Ge1-ySny/p-Ge1-zSnz type structures with a single defected interface. The devices exhibited sizable electroluminescence and good rectifying behavior as evidenced by the low dark currents in the I-V measurements. The formation of working diodes with higher Sn content up to 16% Sn was implemented by using more advanced n-Ge1-xSnx/i-Ge1-ySny/p-Ge1-zSnz architectures incorporating Ge1-xSnx intermediate layers (x ∼ 12% Sn) that served to mitigate the lattice mismatch with the Ge platform. This yielded fully coherent diode interfaces devoid of strain relaxation defects. The electrical measurements in this case revealed a sharp increase in reverse-bias dark currents by almost two orders of magnitude, in spite of the comparable crystallinity of the active layers. This observation is attributed to the enhancement of band-to-band tunneling when all the diode layers consist of direct gap materials and thus has implications for the design of light emitting diodes and lasers operating at desirable mid-IR wavelengths. Possible ways to engineer these diode characteristics and improve carrier confinement involve the incorporation of new barrier materials, in particular, ternary Ge1-x-ySixSny alloys. The possibility of achieving type-I structures using binary and ternary alloy combinations is discussed in detail, taking into account the latest experimental and theoretical work on band offsets involving such materials.

show abstract

Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Direct gap Ge1-ySny alloys: Fabrication and design of mid-IR photodiodes

Senaratne

Wallace

Gallagher

et al. 2016

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…The concentrations of Sn, Si, and Ge as a function of depth in the Ge materials is shown in Figure 7. At the green line (30 nm depth), the ratio of Si:Sn is 3.7, which presents a lattice matched alloy with the Ge substrate [10,11]. This strain-free layer is more stable structure than Ge 1-y Sn y structure and shows enhanced optical properties.…”

Section: Resultsmentioning

confidence: 99%

Feasibility of Formation of Ge1-x-y Six Sny Layers With High Sn Concentration via Ion Implantation

Holliday

Young

Singh

et al. 2020

J. Nucl. Phy. Mat. Sci. Rad. A.

View full text Add to dashboard Cite

By increasing the Sn concentration in Ge1-ySny and Ge1-x-ySixSny systems, these materials can be tuned from indirect to direct bandgap along with increasing electronic and photonic properties. Efforts have been made to synthesize Sn-Ge and Ge-Si-Sn structures and layers to produce lower energy direct bandgap materials. Due to low solid solubility of Sn in Ge and Si-Ge layers, high concentrations of Sn are not achieved by traditional synthesis processes such as chemical vapor deposition or molecular beam epitaxy. Implantation of Sn into Si-Ge systems, followed by rapid thermal annealing or pulse laser annealing, is shown to be an attractive technique for increasing Sn concentration, which can increase efficiencies in photovoltaic applications. In this paper, dynamic ion-solid simulation results are presented. Simulations were performed to determine optimal beam energy, implantation order, and fluence for a multi-step, ion-implantation based synthesis process.

show abstract

“…One of the reasons for the absence of findings is the low solid solubility of Sn into Ge (∼1 at%) and Si (∼0.1 at%). 10) Researchers have made an effort to introduce Sn atoms exceeding the solubility limit into substitutional sites of Si, Ge, and Si 1-x Ge x crystals by thin-film growth under non-equilibrium conditions and have successfully demonstrated the formation of Si 1-x Sn x , 7,11) Ge 1-x Sn x , [4][5][6][12][13][14][15] and Si 1-x-y Ge x Sn y [16][17][18][19][20][21] thin films. Recently, we reported the local structure formed in Ge-rich Si 1-x-y Ge x Sn y films by an extended X-ray absorption fine structure (EXAFS) technique.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity and inelastic X-ray scattering measurements on SiGeSn polycrystalline alloy

Shimura

Iwamoto

Yokogawa

et al. 2021

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

The impact of Sn on Si1-xGex through its thermal conductivity and phonon properties was investigated to develop an attractive material for thermoelectric devices. The Si-rich polycrystalline Si1-x-yGexSny alloy was synthesized by ball-milling technique. The as-synthesized alloy had substitutional Sn content of 1.60%, which it maintained as high as 0.54% after sintering at 1000 °C. The thermal conductivity was found to be reduced by the introduction of this tiny amount of Sn. Inelastic X-ray scattering measurements were carried out and we observed the longitudinal acoustic phonon mode superimposed along all crystallographic directions. In addition, the signal that originated from a local vibration at the Ge-related local structure was also successfully detected. It was found that the introduction of Sn affects the local vibration mode in the alloy. It is proposed that the incorporation of Sn atom into the local structure to make Ge–Sn pairs be considered to reduce the material’s thermal conductivity in addition to the mass difference effect.

show abstract

Experimental observation of type-I energy band alignment in lattice-matched Ge1−x−ySixSny/Ge heterostructures

Cited by 28 publications

References 25 publications

Direct gap Ge1-ySny alloys: Fabrication and design of mid-IR photodiodes

Direct gap Ge1-ySny alloys: Fabrication and design of mid-IR photodiodes

Feasibility of Formation of Ge1-x-y Six Sny Layers With High Sn Concentration via Ion Implantation

Thermal conductivity and inelastic X-ray scattering measurements on SiGeSn polycrystalline alloy

Contact Info

Product

Resources

About