Abstract
Homogenous aSi1−xAlxHy alloyed thin films, made by magnetron sputtering, has been found to exhibit tunable band gap and dielectric constant depending on their composition. The optical properties of alloys are largely defined by their electronic structure, which is is strongly influenced by interatomic charge transfer. In this work we have quantified interatomic charge transfer between Si, Al and H in aSi1−xAlxHy thin-films, with and . Charge transfer was found experimentally using x-ray photoelectron spectroscopy, by incorporating Auger parameter data into the Thomas and Weightman model. Both the perfect and imperfect screening models were tested, and the results were compared to models calculated using density functional theory based molecular dynamics. Using imperfect screening properties of Si and Al resulted in an excellent agreement between the experimental and computational results. Alloying aSi with Al is associated with donation of electrons from Al to Si for y = 0. For y > 0 electrons are transferred away from both Al and Si. The change in Si valence charge increases linearly with increasing band gap and decreasing dielectric constant. These relationships can be used as a quick guide for the evaluation of the Si valence charge and subsequently optoelectronic properties, at specific Al/Si ratios.
Highlights
Increasing demand for low-cost and non-toxic optoelectronic materials, such as solar cells and light-emitting diodes (LEDs), requires development of new types of materials [1,2,3]
As previously reported [7], the aSiAl:H film exhibit a homogenous amorphous structure of silicon alloyed with Al
The dielectric constants were found at an energy of 0.7 eV
Summary
Increasing demand for low-cost and non-toxic optoelectronic materials, such as solar cells and light-emitting diodes (LEDs), requires development of new types of materials [1,2,3]. Hydrogenated amorphous silicon (aSi:H) is currently being used in heterojunction solar cells. Nontoxic, and has a band gap in the appropriate range (1–2 eV). Its high absorption coefficient resulting from the presence of dangling bonds in the structure enables all optical transitions. Passivating the dangling bonds with hydrogen increases the band gap of the material [4].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
