Diffusion and doping issues in germanium

Bracht, H.; Schneider, Stefan W.; Kube, R.

doi:10.1016/j.mee.2010.10.013

Cited by 33 publications

(31 citation statements)

References 43 publications

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“…In this context we refer to recent experiments on RED in Ge that demonstrate strong athermal RED effects, i.e., increasing RED with decreasing temperature. This unusual behavior is related to the presence of highly mobile Ge interstitials, 15,16 whose concentration increases with decreasing temperature due to the decreasing number of vacancies available for annihilation. 17 Finally, with continuing ion-beam treatment, the crystalline matrix becomes amorphous and the mixing mechanism changes.…”

Section: Resultsmentioning

confidence: 99%

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Ion-beam mixing in crystalline and amorphous germanium isotope multilayers

Bracht¹,

Radek²,

Kube³

et al. 2011

Journal of Applied Physics

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Gallium (Ga) implantation induced self-atom mixing in crystalline and amorphous germanium (Ge) is investigated utilizing isotopically controlled Ge multilayer structures grown by molecular beam epitaxy. The distribution of the Ga ions and the ion-beam induced depth-dependent mixing of the isotope structure was determined by means of secondary ion mass spectrometry. Whereas the distribution of Ga in the crystalline and amorphous Ge is very similar and accurately reproduced by computer simulations based on binary collision approximation (BCA), the ion-beam induced self-atom mixing is found to depend strongly on the state of the Ge structure. The experiments reveal stronger self-atom mixing in crystalline than in amorphous Ge. Atomistic simulations based on BCA reproduce the experimental results only when unphysically low Ge displacement energies are assumed. Analysis of the self-atom mixing induced by silicon implantation confirms the low displacement energy deduced within the BCA approach. This demonstrates that thermal spike mixing contributes significantly to the overall mixing of the Ge isotope structures. The disparity observed in the ion-beam mixing efficiency of crystalline and amorphous Ge indicates different dominant mixing mechanisms. We propose that self-atom mixing in crystalline Ge is mainly controlled by radiation enhanced diffusion during the early stage of mixing before the crystalline structure turns amorphous, whereas in an already amorphous state self-atom mixing is mediated by cooperative diffusion events.

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Section: Resultsmentioning

confidence: 99%

“…RED in Ge is dominated by self-interstitials that result from Frenkel pairs formed by irradiation. 15,16,20 When the solid becomes amorphous, the mixing mechanisms changes. In the amorphous state self-atom mixing is rather mediated by cooperative jump processes than by diffusion events associated with native point defects.…”

Section: Discussionmentioning

confidence: 99%

Ion-beam mixing in crystalline and amorphous germanium isotope multilayers

Bracht¹,

Radek²,

Kube³

et al. 2011

Journal of Applied Physics

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“…This correlation is supported by the diffusion behavior of arsenic (As) in Ge. Under thermal equilibrium As diffusion is mediated by V 7,10 and under irradiation no significant enhancement of As diffusion is observed 28,36 . Obviously, the concentration of V under irradiation equals the concentration under thermal equilibrium.…”

Section: Modeling Diffusion Under Irradiationmentioning

confidence: 91%

“…This is a consequence of the disparity in the annihilation behavior of I and V at the Ge surface (see section IV A). The absence of any radiation enhanced diffusion of arsenic in Ge 36 , whose diffusion is mainly mediated by V 7,10 , and the heavily enhanced diffusion of B 25,26,28 demonstrates that the migration of B under irradiation can not be mediated by V . Accordingly, B diffusion in Ge under irradiation must be controlled by self-interstitials and the following defect reactions are considered for modeling its diffusion behavior…”

Section: B Boron Diffusionmentioning

confidence: 98%

“…This is consistent with theoretical predictions that reveal a formation enthalpy of I being 1-2 eV higher than for V [17][18][19][20][21][22][23][24] . However, recent experiments on self-and dopant diffusion in Ge under proton irradiation indicate the dominance of I rather than of V [25][26][27][28][29] . This observation is of scientific and technologic significance as it provides not only information about the interaction of dopant atoms with I but also insight into the property of the Ge surface that supports an I supersaturation and V thermal equilibrium under irradiation.…”

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Radiation-enhanced self- and boron diffusion in germanium

et al. 2013

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We report experiments on proton irradiation enhanced self-and boron (B) diffusion in germanium (Ge) for temperatures between 515 • C and 720 • C. Modeling of the experimental diffusion profiles measured by means of secondary ion mass spectrometry is achieved on the basis of the Frenkel pair reaction and the interstitialcy and dissociative diffusion mechanisms. The numerical simulations ascertain concentrations of Ge interstitials and B-interstitial pairs that deviate by several orders of magnitude from their thermal equilibrium values. The dominance of self-interstitial related defects under irradiation leads to an enhanced self-and B diffusion in Ge. Analysis of the experimental profiles yields data for the diffusion of self-interstitials (I) and the thermal equilibrium concentration of BI pairs in Ge. The temperature dependence of these quantities provides the migration enthalpy of I and formation enthalpy of BI that are compared with recent results of atomistic calculations. The behavior of self-and B diffusion in Ge under concurrent annealing and irradiation is strongly affected by the property of the Ge surface to hinder the annihilation of self-interstitials. The limited annihilation efficiency of the Ge surface can be caused by donor-type surface states favored under vacuum annealing but the physical origin remains unsolved.

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Point Defects in Semiconductors

Pizzini¹

2015

Physical Chemistry of Semiconductor Materials and Processes

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Diffusion and doping issues in germanium

Cited by 33 publications

References 43 publications

Ion-beam mixing in crystalline and amorphous germanium isotope multilayers

Ion-beam mixing in crystalline and amorphous germanium isotope multilayers

Radiation-enhanced self- and boron diffusion in germanium

Point Defects in Semiconductors

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