Ge–Sn semiconductors for band-gap and lattice engineering

Bauer, Matthew R.; Taraci, J. L.; Tolle, John; Chizmeshya, Andrew; Zollner, Stefan; Smith, David J.; Menéndez, José; Hu, C. W.; Kouvetakis, John

doi:10.1063/1.1515133

Cited by 262 publications

(180 citation statements)

References 10 publications

Supporting

Mentioning

167

Contrasting

Order By: Relevance

“…An alternative route is based on SnCl 4 , 13,14 which has the advantage of being favored in certain industrial tools. The SnD 4 precursor was initially demonstrated in combination with digermane (Ge 2 H 6 ), 1 but subsequent work has shown that trigermane (Ge 3 H 8 ) is ideally compatible with SnD 4 , 15 leading to a nearly equal incorporation efficiency for Ge and Sn. This makes it very simple to control the film composition by varying the precursor gaseous mixture.…”

Section: Synthetic Approachmentioning

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

Self Cite

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: Synthetic Approachmentioning

confidence: 99%

“…1 This progress is remarkable if one considers that the roomtemperature solid solubility of Sn in Ge is less than 1%. 2,3 In spite of this thermodynamic constraint, however, devicequality alloys with very high metastable Sn concentrations are now routinely synthesized.…”

Section: Introductionmentioning

confidence: 99%

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

Senaratne

Wallace

Gallagher

et al. 2016

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…Based on this thermodynamics limitation, the first monocrystalline GeSn growth techniques developed were based on out of equilibrium growth conditions using ultimately low temperatures and reduced pressures. 9,10 Whereas the necessity of growing GeSn at low temperature is well understood (according to GeSn phase diagram), the necessity of using reduced pressure to enable metastable GeSn growth has never been confirmed experimentally. This letter shows metastable GeSn epitaxial growth on Ge substrate, with Sn content up to 8%, using an atmospheric pressure-chemical vapor deposition (AP-CVD) technique.…”

mentioning

confidence: 99%

“…10,13 Further anneals were then done after growth on the GeSn layers in order to assess their thermal stability. Anneals were performed in a rapid thermal anneal equipment at 400 C and 500 C for 10 and 30 min in pure N 2 .…”

mentioning

confidence: 99%

Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

Vincent

Gencarelli

Bender

et al. 2011

Applied Physics Letters

196

155

View full text Add to dashboard Cite

“…This concept of structural engineering via phase segregation by modifying the atomic percentage ratios of the metal layer may also be applicable to other systems with negligible solid solubility limits such as SnGe and AgGe. 12 Additionally, in the future, detailed theoretical calculations of the relevant energies and the nanoscale phase diagram of the system are needed to further shed light on the kinetics of the proposed structural nanoengineering process.…”

mentioning

confidence: 99%

Nanoscale Structural Engineering via Phase Segregation: Au−Ge System

et al. 2010

View full text Add to dashboard Cite

A tunable structural engineering of nanowires based on template-assisted alloying and phase segregation processes is demonstrated. The Au-Ge system, which has a low eutectic temperature and negligible solid solubility (<10 -3 atom %) of Au in Ge at low temperatures, is utilized. Depending on the Au concentration of the initial nanowires, final structures ranging from nearly periodic nanodisk patterns to core/shell and fully alloyed nanowires are produced. The formation mechanisms are discussed in detail and characterized by in situ transmission electron microscopy and energy-dispersive spectrometry analyses. Electrical measurements illustrate the metallic and semiconducting characteristics of the fully alloyed and alternating Au/Ge nanodisk structures, respectively. KEYWORDS Phase segregation, nanowires, nanoscale diffusion, supercooling T he ability to control the size, structure, composition, and morphology of nanowires (NWs) presents an ideal platform for elucidating nanoscale phenomena while exploring a wide range of potential technological applications. 1 In the past, researchers have demonstrated the synthesis of NW materials with tailored composition by altering the precursors during the growth process, for instance, resulting in superlattice structures with unique electrical and optical properties. 2 Here, we present a different approach, involving the postgrowth engineering of the NW structure and composition through the alloying and phase segregation of binary compounds induced by thermal annealing. As an example, we utilized the Au-Ge system which has a low eutectic temperature (361°C) with negligible Au solid solubility (<10 -3 atom %) in Ge at room temperature. 3 In this approach, Ge/Au core/shell NWs with a HfO 2 capping layer are first prepared and then thermally annealed during which a wide range of nanostructures are controllably formed depending on the initial Au content and the annealing conditions. This approach presents a novel route for controlling the NW composition and structure with potential implications for applications in phase change memory, optoelectronic, and electronic nanodevices.The overall concept of this structural nanoengineering process is schematically illustrated in Figure 1. Ge NWs are first synthesized by the vapor-liquid-solid process as previously reported elsewhere 4 with diameters d ) 50-60 nm ( Figure 1a). Next, a Au layer is sputtered on the surface of the Ge NW arrays with thickness of t Au ) 2-15 nm ( Figure 1b). The thickness of the sputtered Au layer determines the overall Au:Ge atomic ratio of the NWs (see Figure S1 in Supporting Information). The NWs are then capped with ∼10 nm thick HfO 2 deposited by atomic layer deposition pubs.acs.org/NanoLett

show abstract

Ge–Sn semiconductors for band-gap and lattice engineering

Cited by 262 publications

References 10 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

Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

Nanoscale Structural Engineering via Phase Segregation: Au−Ge System

Contact Info

Product

Resources

About