Influence of In0.56Ga0.44P/Ge heterostructure on diffusion of phosphorus in germanium during the formation of multiple solar cells

Kobeleva, S. P.; Anfimov, I. M.; Yurchuk, Sergey; Vygovskaya, E. A.; Zhalnin, B.V.

doi:10.1134/s1063785013010173

Cited by 4 publications

(6 citation statements)

References 5 publications

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“…The gallium, phosphorus and ger-manium profiles were measured by SIMS on a PHI-6600. As shown elsewhere [20] the phosphine gas treatment introduces a small phosphorus quantity, its main quantity being added during further layer growth and hence the diffusion time is 2.6 min. The 3 and 5 Mendeleev Table group elements form well-known compounds and therefore Ga and P co-diffusion analysis should take into account possible formation of complexes.…”

Section: Specimen Preparationmentioning

confidence: 84%

“…During first MJSC stage synthesis phosphorus diffuses from the InGaP buffer layer to heavily gallium doped germanium. As shown earlier [20] the Ga solubility at the InGaP/Ge interface is higher than that of P and therefore two p-n junctions form and the phosphorus profile has 3 sections delimited by these p-n junctions [20][21][22]. The aim of this work is to analyze diffusion profiles and calculate phosphorus diffusion coefficients in germanium for formation of the first MJSC stage p-n junction.…”

Section: Introductionmentioning

confidence: 96%

“…The development of multi-junction solar cell (MJSC) technology raises the interest to germanium as substrate and first stage material for А 3 В 5 compound base MJSC [17][18][19][20]. During first MJSC stage synthesis phosphorus diffuses from the InGaP buffer layer to heavily gallium doped germanium.…”

Section: Introductionmentioning

confidence: 99%

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Coordinate dependent diffusion analysis of phosphorus diffusion profiles in gallium doped germanium

Kobeleva¹,

Anfimov²,

Turutin³

et al. 2018

MoEM

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We have analyzed phosphorus diffusion profiles in an In0.01Ga0.99As/In0.56Ga0.44P/Ge germanium structure during phosphorus co-diffusion with gallium for synthesis of the germanium subcell in multi-junction solar cells.. Phosphorus diffused from the In0.56Ga0.44P layer simultaneously with gallium diffusion into the heavily gallium doped germanium substrate thus determining the specific diffusion conditions. Most importantly, gallium and phosphorus co-diffusion produces two p–n junctions instead of one. The phosphorus diffusion profiles do not obey Fick’s laws. The phosphorus diffusion coefficient DP depth distribution in the specimen has been studied using two methods, i.e., the Sauer–Freise modification of the Boltzmann–Matano method and the coordinate dependent diffusion method. We show that allowance for the drift component in the coordinate dependent diffusion method provides a better DP agreement with literary data. Both methods suggest the DP tendency to grow at the heterostructure boundary and to decline closer to the main p–n junction. The DP growth near the surface p–n junction the field of which is directed toward the heterostructure boundary and its decline near the main p–n junction with an oppositely directed field, as well as the observed DP growth with the electron concentration, suggest that the negatively charged VGeP complexes diffuse in the heterostructure by analogy with one-component diffusion.

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Section: Specimen Preparationmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 96%

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Coordinate dependent diffusion analysis of phosphorus diffusion profiles in gallium doped germanium

Kobeleva¹,

Anfimov²,

Turutin³

et al. 2018

MoEM

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“…It was found that p-n junction depth weakly depends on the diffusion time. In [24,25], P and Ga profiles in the heterostructure In 0.01 Ga 0.99 As/In 0.56 Ga 0.44 P/Ge were investigated. p-n junction of this element was formed at 635 C by phosphorus diffusion from In 0.56 Ga 0 .…”

Section: Diffusion Of Phosphorus In Ingaas/ingap/p Heterostructuresmentioning

confidence: 99%

“…As it was expected, phosphorus profile has two parts: Fickian type near the surface in p-region (C Ga > C P ) and box-shaped between p-n junctions where n > n i . Unfortunately using diffusion coefficient with quadratic and cubic dependencies, the P profile could not be accurately described [25].…”

Section: Advanced Materials and Device Applications With Germaniummentioning

confidence: 99%

Phosphorus and Gallium Diffusion in Ge Sublayer of In0.01Ga0.99As/In0.56Ga0.44P/Ge Heterostructures

Petrovna¹,

Anfimov²,

Yurchuk³

2018

Advanced Material and Device Applications With Germanium

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This chapter gives a short review on dopant diffusion in germanium and specifies the underlying mechanisms of diffusion that involve the point defects. Box-shaped diffusion profiles are discussed that may be described as the phosphorus diffusion controlled by doubly ionized vacancies. In this mechanism, the diffusion coefficient depends on the electron concentration. The particulars of P and Ga diffusion profiles in the Ga-doped substrate of In 0.01 Ga 0.99 As/In 0.56 Ga 0.44 P/Ge heterostructures for multilayer solar cells are discussed. To calculate the diffusion coefficient, two methods were used: the Boltzmann-Matano (version of Sauer-Freise) and the coordinate-dependent diffusion analysis. It is established that coordinate-dependent diffusion analysis, which involves drift components together with diffusion components for diffusion profile description, is more suitable for description of the experimental profiles in such structures near p-n junction. A strong influence of intrinsic electric field on the dopant diffusivity was detected.

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Degradation of Ge subcells by thermal load during the growth of multijunction solar cells

Barrigón

Ochoa

García

et al. 2017

Progress in Photovoltaics

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Germanium solar cells are used as bottom subcells in many multijunction solar cell designs. The question remains whether the thermal load originated by the growth of the upper layers of the multijunction solar cell structure affects the Ge subcell performance. Here, we report and analyze the performance degradation of the Ge subcell due to such thermal load in lattice‐matched GaInP/Ga(In)As/Ge triple‐junction solar cells. Specifically, we have detected a quantum efficiency loss in the wavelength region corresponding to the emitter layer (which accounts for up to 20% loss in equivalent JSC) and up to 55 mV loss in VOC of the Ge subcell as compared with analogous devices grown as single‐junction Ge solar cells on the same type of substrates. We prove experimentally that there is no direct correlation between the loss in VOC and the doping level of the base. Our simulations show that both the JSC and VOC losses are consistent with a degradation of the minority carrier properties at the emitter, in particular at the initial nanometers of the emitter next to the emitter/window heterointerface. In addition, we also rule out the gradual emitter profile shape as the origin of the degradation observed. Our findings underscore the potential to obtain higher efficiencies in Ge‐based multijunction solar cells if strategies to mitigate the impact of the thermal load are taken into consideration.

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Influence of In0.56Ga0.44P/Ge heterostructure on diffusion of phosphorus in germanium during the formation of multiple solar cells

Cited by 4 publications

References 5 publications

Coordinate dependent diffusion analysis of phosphorus diffusion profiles in gallium doped germanium

Coordinate dependent diffusion analysis of phosphorus diffusion profiles in gallium doped germanium

Phosphorus and Gallium Diffusion in Ge Sublayer of In0.01Ga0.99As/In0.56Ga0.44P/Ge Heterostructures

Degradation of Ge subcells by thermal load during the growth of multijunction solar cells

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