Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon During Annealing

Abstract

• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Correlating the silicon surface passivation to the nanostructure of low-temperature a-Si:H after rapid thermal annealing

“…This difference in size distribution can be the reason for the observed difference in the broadening parameter B r in the Tauc-Lorentz analysis, i.e., the less disordered and more relaxed 50 C sample allows for a wider size distribution of open volume deficiencies in the material. Furthermore, the size distribution difference after annealing is in line with the idea that agglomeration and effusion of open volume deficiencies take place less efficiently in denser materials, 42 which-in this work-are the films deposited at higher temperatures. It can thus be argued that the final annealed state of the sample deposited at 10 C is characterized by a narrower distribution of large open volume deficiencies in comparison to the 50 C sample.…”

“…Interestingly, this is in line with the findings in an annealing study of various a-Si:H bulk materials where it was found that the migration of open volume deficiencies evolves more efficiently in less dense materials. 42 Note that on long timescales, all the samples indeed show a decrease in lifetime, hinting at depassivation of the a-Si:H/c-Si interface caused by the breaking of Si-H bonds at the c-Si surface. The samples prepared at 75 and 100 C did not show any passivation both in the as-deposited state and after annealing due to the occurrence of epitaxy, and have therefore not been investigated further.…”

“…The corresponding enhanced migration of both open volume deficiencies and hydrogen during annealing can prove to be beneficial when trying to increase the c-Si surface passivation quality. 42 In order to unravel the mechanism behind the rapid passivation and its relation to the a-Si:H nanostructure, the evolution of the minority carrier lifetime, optical properties, and H bonding configuration has been studied for annealing times ranging from 30 s to 10 4 min. As can be seen in Fig.…”

“…Although this is the dominant process during time period (I), there is likely also some clustering of open volume deficiencies and hydrogen effusion, as described elsewhere for bulk a-Si:H, but these processes appear not to play a dominant role on such short timescales. 10,42 Subsequently, on the moderate time scale (II), the DB passivation by hydrogen at the a-Si:H/c-Si interface stays approximately intact despite the more dominant role of open volume deficiency clustering and hydrogen effusion. This means that these three processes are rather equilibrated, although the loss of hydrogen from the film is already becoming apparent in the slow decrease of the minority carrier lifetime.…”

Metastable Refractive Index Manipulation in Hydrogenated Amorphous Silicon for Reconfigurable Photonics

“…Consequently, the relation between these metastable properties and the optical properties (refractive index, n and extinction coefficient, k ) was characterized using spectroscopic ellipsometry (SE), predominantly in the UV spectrum . While considerable scientific effort has been spent on investigating the phenomenon in photovoltaic cells, its potential application for reconfigurable photonics by exploiting the metastable optical properties has remained unexplored …”