Ambient stability of wet chemically passivated germanium wafer for crystalline solar cells

Swain, Bibhu P.; Takato, Hidetaka; Liu, Zhengxin; Sakata, Isao

doi:10.1016/j.solmat.2010.05.012

Cited by 13 publications

(10 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ge films grown on Si can be close to this limit, because the interface recombination velocity can be as high as s int =4000 cm/s, whereas the surface recombination velocity is approximately s sur = 140 cm/s. 30,31 On the other hand, the observation of a significant PL intensity increase in our samples implies that for Ge 1−y Sn y on Ge-buffered Si s int < s sur 0 , where s sur 0 is the surface recombination velocity prior to passivation. This means s int ∼ 100 cm/s.…”

Section: Ge Indmentioning

confidence: 62%

Advances in Light Emission from Group-IV Alloys via Lattice Engineering and n-Type Doping Based on Custom-Designed Chemistries

et al. 2014

View full text Add to dashboard Cite

Intrinsic and n-type Ge1–y Sn y alloys with y = 0.003–0.11 have been grown on Ge-buffered Si via reactions of Ge3H8 and SnD4 hydrides using UHV-CVD techniques. The films exhibit large thicknesses (t > 600 nm), low dislocation densities (107/cm2), planar surfaces (AFM RMS ≈ 2 for intrinsic films) and mostly relaxed microstructures, making them suitable for subsequent characterization of the emission properties using photoluminescence (PL) spectroscopy. The PL spectra are acquired at room temperature and show tunable and distinct direct and indirect gap emission peaks versus composition. The peak intensity in a given sample is found to increase by exposing the layers to hydrogen plasma, indicating that surface passivation plays an important role in eliminating carrier recombination traps. The PL intensity is further increased by n-type doping with P/As atoms at levels 0.8–7 × 1019 cm–3using P(GeH3)3, P(SiH3)3, and As(SiH3)3 precursors, indicating that desirable direct gap conditions can be approached even at relatively modest 6–8% Sn contents. The indirect and direct gap energies of the samples are then used to determine the direct gap cross over point at ∼9% Sn. Collectively the results in this paper show that strong light emission can be generated in this class of narrow gap alloys by adjusting the Sn content, subjecting the samples to post growth passivation treatments or doping the system n-type. The influence of precursor chemistry on the activation properties and optical behavior of the materials is explored with the objective to optimize the PL response near the indirect–direct gap threshold. New methods embodying environmentally safe conditions are designed to produce the dopant compounds in high purity for application in future generation working devices requiring enhanced IR optical performance.

show abstract

Section: Ge Indmentioning

confidence: 62%

Advances in Light Emission from Group-IV Alloys via Lattice Engineering and n-Type Doping Based on Custom-Designed Chemistries

et al. 2014

View full text Add to dashboard Cite

show abstract

“…46 However, we believe that the HF treatment in our MOSCAP fabrication process not only removed the native oxide, but also acted as effective surface passivation. 47,48 Besides, dangling bonds would also be well passivated by the forming gas annealing in hydrogen atmosphere. 49 What's more, contraction of dangling bonds due to surface reconstruction might occur during MacEtch process, thus leading to the preservation of high quality surface after etching.…”

Section: Surface Quality Characterization Of Ge Inverted Pyramids: Mo...mentioning

confidence: 99%

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The recombination velocity s at a bare Ge surface is about 140 cm/s. 29 On the other hand, the interface recombination velocity at a dislocated Si-Ge interface can be as high as s = 4000 cm/s. 30 Using this value for a film thickness W = 1 μm, the effective lifetime becomes τ L = W 2s = 12 ns, so that τ ΓL τ L = 10 -4…”

Section: Non-equlibrium Modelmentioning

confidence: 99%

Direct versus indirect optical recombination in Ge films grown on Si substrates

et al. 2011

View full text Add to dashboard Cite

Abstract:The optical emission spectra from Ge films on Si are markedly different from their bulk Ge counterparts. Whereas bulk Ge emission is dominated by the material's indirect gap, the photoluminescence signal from Ge films is mainly associated with its direct band gap. Using a new class of Ge-on-Si films grown by a recently introduced CVD approach, we study the direct and indirect photoluminescence from intrinsic and doped samples and we conclude that the origin of the discrepancy is the lack of self-absorption in thin Ge films combined with a deviation from quasi-equilibrium conditions in the conduction band of undoped films. The latter is confirmed by a simple model suggesting that the deviation from quasi-equilibrium is caused by the much shorter recombination lifetime in the films relative to bulk Ge.

show abstract

Ambient stability of wet chemically passivated germanium wafer for crystalline solar cells

Cited by 13 publications

References 14 publications

Advances in Light Emission from Group-IV Alloys via Lattice Engineering and n-Type Doping Based on Custom-Designed Chemistries

Advances in Light Emission from Group-IV Alloys via Lattice Engineering and n-Type Doping Based on Custom-Designed Chemistries

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

Direct versus indirect optical recombination in Ge films grown on Si substrates

Contact Info

Product

Resources

About