Diffusion and defect reactions between donors, C, and vacancies in Ge. I. Experimental results

Brotzmann, S.; Bracht, H.; Hansen, J. Lundsgaard; Larsen, A. Nylandsted; Simoen, Eddy; Häller, E. E.; Christensen, J. S.; Werner, P.

doi:10.1103/physrevb.77.235207

Cited by 125 publications

(177 citation statements)

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“…C atoms have been observed to be relatively immobile; however, they can retard the diffusion of phosphorus ͑P͒, arsenic ͑As͒, and antimony ͑Sb͒ atoms in Ge. 26,27 Recent experimental studies by Silvestri et al 15 ͑using SIMS͒ concluded that Si diffusion in Ge is mediated by V with an activation enthalpy of 3.32 eV, whereas previous studies determined values in the range of 2.9-3.47 eV. [12][13][14] The diffusion of Si in Ge is slower than Ge self-diffusion.…”

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confidence: 94%

Vacancy-mediated dopant diffusion activation enthalpies for germanium

Chroneos

Bracht

Grimes

et al. 2008

Applied Physics Letters

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Electronic structure calculations are used to predict the activation enthalpies of diffusion for a range of impurity atoms ͑aluminium, gallium, indium, silicon, tin, phosphorus, arsenic, and antimony͒ in germanium. Consistent with experimental studies, all the impurity atoms considered diffuse via their interaction with vacancies. Overall, the calculated diffusion activation enthalpies are in good agreement with the experimental results, with the exception of indium, where the most recent experimental study suggests a significantly higher activation enthalpy. Here, we predict that indium diffuses with an activation enthalpy of 2.79 eV, essentially the same as the value determined by early radiotracer studies. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2918842͔ Germanium ͑Ge͒ has the potential to replace silicon ͑Si͒ in advanced nanoelectronic devices because of the higher mobility of holes and electrons, compatibility with Si manufacturing processes, increased dopant solubility, and smaller band gap. 1 The precise control required for the fabrication of these devices would be greatly aided by an accurate determination of the diffusion properties of impurities in Ge. 2 This is particularly important for donor impurities for which activation control can be problematic. 3 In previous studies, it has been concluded that most impurities mainly occupy substitutional lattice sites in Ge and, with the exception of boron ͑B͒, dopant diffusion is mainly mediated by vacancies ͑V͒ as interstitial mechanisms typically have significantly higher activation enthalpies. 2, Aluminium ͑Al͒, gallium ͑Ga͒, indium ͑In͒, and B are acceptor atoms that can potentially be used as p-type dopants in Ge technology. Recent experiments 4 on B diffusion in Ge yield an activation enthalpy of 4.65 eV that agrees with earlier results, but the absolute values of the B diffusion coefficients are several orders of magnitude lower than those reported earlier. 5 Previous experimental studies on Al diffusion yield activation enthalpies in the range of 3.2-3.45 eV. 6,7 Södervall et al. 8 obtained an activation enthalpy of 3.31 eV for Ga diffusion in Ge. This value is supported by the more recent experimental studies of Riihimäki et al. 9 who determined an activation enthalpy of 3.21 eV for Ga diffusion in Ge via a V-mediated mechanism. The spread in the data reported for the activation enthalpy of In diffusion in Ge is especially large ͑0.85 eV͒. The radiotracer studies of Pantaleev 10 suggest a value of 2.78 eV, whereas the In profiles measured by Dorner et al. 11 by means of secondary ion mass spectrometry ͑SIMS͒ yield a value of 3.63 eV.Carbon ͑C͒, Si, and tin ͑Sn͒ are important isovalent impurities. C atoms have been observed to be relatively immobile; however, they can retard the diffusion of phosphorus ͑P͒, arsenic ͑As͒, and antimony ͑Sb͒ atoms in Ge. 26,27 Recent experimental studies by Silvestri et al. 15 ͑using SIMS͒ concluded that Si diffusion in Ge is mediated by V with an activation enthalpy of 3.32 eV, whereas previous studies ...

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confidence: 94%

Vacancy-mediated dopant diffusion activation enthalpies for germanium

Chroneos

Bracht

Grimes

et al. 2008

Applied Physics Letters

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135

113

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“…The topmost near surface 100 nm thick natural Ge layer is amorphous and grown on 200 nm thick crystalline Ge. This sample structure was designed for studying the simultaneous diffusion of self-and dopant atoms, whereto the dopant of interest was implanted into the top amorphous layer 8 . Structure #2 consists of five alternating 70 Ge(100 nm)/ nat Ge(100 nm) bilayers with a top 50 nm thick natural crystalline Ge layer.…”

Section: Methodsmentioning

confidence: 99%

“…The single acceptor nature of B − s is generally accepted. Experiments on the simultaneous diffusion of n-type dopants and self-atoms demonstrate that the vacancy in Ge is doubly negatively charged even under electronically intrinsic conditions 8,9 . Investigations of the electronic properties of defects in Ge resulting from electron irradiation reveal an acceptor energy level of 0.14 eV above the valence band and two donor states with energy positions of 0.08 eV and 0.24 eV below the conduction band of Ge 42 .…”

Section: B Boron Diffusionmentioning

confidence: 99%

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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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“…5 The latter has been associated with a vacancy-mediated diffusion mechanism, 6 as opposed to Si, wherein donors diffuse through both vacancies (V's) and interstitials. 7 Furthermore, donor passivation is known to be a problem in Ge, and it has been attributed to the formation of vacancy-donor ðV M -D N Þ complexes in a few experimental [8][9][10][11] and computational 12 studies. In a recent positron study on highly n-type Ge obtained by diffusion doping, an extensive formation of V-D N complexes was found with the common donors D 2 {As, P, Sb}.…”

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confidence: 99%