Diffusion in Semiconductors

Shaw, D.

doi:10.1007/978-0-387-29185-7_6

Cited by 3 publications

(2 citation statements)

References 72 publications

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“…25−28 In the case of metals, hydrogen has been shown to increase the mobility of vacancy defects, 28,29 while in semiconductors, hydrogen retards vacancy diffusion. 22,30,31 Here, we exploit this effect as a chemical means to stabilize surface mass flow during ion irradiation. We achieve smooth surfaces during ion beam processing of crystalline elemental and compound semiconductors by using the combination of sample heating and hydrogen.…”

Section: ■ Introductionmentioning

confidence: 99%

Suppression of Surface Roughening during Ion Bombardment of Semiconductors

2022

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Ion beams are used routinely for processing of semiconductors, particularly sputtering, ion implantation, and direct-write fabrication of nanostructures. However, the utility of ion beam techniques is limited by crystal damage and surface roughening. Damage can be reduced or eliminated by performing irradiation at elevated temperatures. However, under these conditions, surface roughening is highly problematic due to thermal mobility of adatoms and surface vacancies. Here, we solve this problem using hydrogen gas, which we use to stabilize surface mass flow and suppress roughening during ion bombardment of elemental and compound semiconductors. We achieve smooth surfaces during ion beam processing and show that the method can be enhanced by radicalizing H2 gas using a remote plasma source. Our approach is broadly applicable and expands the utility of ion beam techniques for the processing and fabrication of functional materials and nanostructures.

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Section: ■ Introductionmentioning

confidence: 99%

Suppression of Surface Roughening during Ion Bombardment of Semiconductors

2022

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“…This is an example of a slow, “substitutional diffusion” process . However, a more expedient mechanism of ionic transport through crystalline materials exhibiting interstitial migration channels is also possible. − Various binary semiconductors (TiO 2 , ZnO, CdS to name a few) contain extended, linear interstitial diffusion pathways that permit the relatively unhindered diffusion of small ions through the interior corridors of their crystalline lattice. The uptake of charge balancing cations by such semiconductor materials upon electrochemical reduction was investigated via electrochemical quartz crystal microbalance studies, which demonstrated a one-to-one correspondence between the extent of reduction of the II–VI semiconductors and their mass gain .…”

Section: Introductionmentioning

confidence: 99%

Classical or Quantum? A Computational Study of Small Ion Diffusion in II–VI Semiconductor Quantum Dots

et al. 2016

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Ion diffusion in semiconductor nanocrystals, or quantum dots (QDs), has gained recognition in recent years as a crucial process for advancing both energy storage and, more generally, the postsynthetic p-type doping chemistry of these materials. In this report, we present first an energetic analysis of group I cations (H+, Li+, and Na+) diffusion in (MX)84 – QDs, with M = Zn, Cd and X = S, Se. The bound solutions to the corresponding one-dimensional nuclear Schrödinger equation were solved for these systems, relying on the discrete variable representation method. From this vantage, the quantum nature of the intercalating ion can be revealed. Evidence for the importance of including quantum effects in the treatment of these diffusion processes is presented, both with the density of energy eigenstates of the intercalating ion and from a comparison of the standard deviation in the population distribution of the intercalating ion to the lattice spacings of its host material. Results suggest that the use of classical mechanics for simulations of the ion diffusion processes in these and other related materials can be a questionable practice for the smallest group I cations. Trends devised herein can be useful to help guide the development of new experimental approaches to postsynthetic doping of semiconductor nanocrystals, and in designing electrode materials for next generation electrochemical energy storage devices.

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Diffusion of Mg dopant in metal-organic vapor-phase epitaxy grown GaN and AlxGa1−xN

Köhler

Gutt

Wiegert

et al. 2013

Journal of Applied Physics

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Diffusion of the p-type dopant Mg in GaN and AlxGa1−xN which is accompanied by segregation and affected by transient effects in metal-organic vapor-phase epitaxy reactors is investigated. We have grown 110 nm thick Mg doped GaN and Al0.1Ga0.9N layers on top of undoped GaN and Al0.1Ga0.9N layers, respectively, in a temperature range between 925 °C and 1050 °C where we placed special emphasis on the lower temperature limit without diffusion to allow separation of Mg transients, diffusion, and segregation. Hereby, AlxGa1−xN layers enable monitoring of the resolution limit by secondary ion mass spectrometry analyses for the respective samples; therefore, thin AlxGa1−xN marker layers are incorporated in the thick GaN layers. We found an upper limit of 1.25 × 1019 cm−3 for diffusing Mg atoms in both sample types. Owing to the marked influence of Mg segregation in Al0.1Ga0.9N, diffusion is only seen by using a GaN cap on top of the Al0.1Ga0.9N layer sequence. Diffusion in Al0.1Ga0.9N is shown to be increased by about 25%−30% compared to GaN. Post growth annealing experiments under conditions equivalent to those used for growth of the Mg doped samples showed negligible diffusion. Comparing the results to well established findings on other doped III-V compounds, diffusion is explained by an interstitial-substitutional mechanism with a diffusion coefficient, which is concentration dependent. Analysis of the temperature dependent diffusivity revealed an activation energy of 5.0 eV for GaN:Mg and 5.2 eV for Al0.1Ga0.9N:Mg.

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Diffusion in Semiconductors

Cited by 3 publications

References 72 publications

Suppression of Surface Roughening during Ion Bombardment of Semiconductors

Suppression of Surface Roughening during Ion Bombardment of Semiconductors

Classical or Quantum? A Computational Study of Small Ion Diffusion in II–VI Semiconductor Quantum Dots

Diffusion of Mg dopant in metal-organic vapor-phase epitaxy grown GaN and AlxGa1−xN

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