Close

Search

Search Menu
Photonics Media Photonics Marketplace Photonics Spectra BioPhotonics EuroPhotonics Vision Spectra Photonics Showcase Photonics ProdSpec Photonics Handbook

Cuprous Iodide Film Shows Promise for Semiconductors, Optoelectronics

Facebook Twitter LinkedIn Email Comments
SAITAMA, Japan, April 9, 2021 — Physicists from RIKEN have taken a step to enhance semiconductor performance, developing a single-crystal thin film of cuprous iodide. The film is atomically flat and free of any defects.

Conventional approaches for fabricating thin films of cuprous iodide without any impurities typically necessitate depositing the film from a solution. Using cuprous iodide, however, which is a halide compound and a highly effective conductor and is stable above room temperature, a solution-based process is unable to generate a high-quality thin film.

A team led Masao Nakamura from the RIKEN Center for Emergent Matter Science instead used molecular beam epitaxy. In the technique, a film is grown on top of a substrate, in a vacuum, and at an elevated temperature. Though the technique is commonly used in semiconductor manufacturing, it is difficult to use for cuprous iodide. The material is highly volatile, meaning that it evaporates easily in the epitaxial process and does not settle easily into the structure of the film.

The team overcame that method by first growing its film at a lower temperature and then increasing it gradually in a two-step process.

A thin film of cuprous iodide crystals (blue) on an indium arsenide substrate (yellow). The sample’s purity was tested by shining photons onto the surface to create electron–hole pairs (red and blue spheres) and monitoring the light that was emitted (white rays). Courtesy of RIKEN Center for Emergent Matter Science
A thin film of cuprous iodide crystals (blue/purple) on an indium arsenide substrate (yellow). The sample’s purity was tested by shining photons onto the surface to create electron-hole pairs (red and blue spheres) and monitoring the light that was emitted (white rays). Courtesy of RIKEN Center for Emergent Matter Science.
Another essential characteristic of the work involved the use of indium arsenide at its substrate; the physical spacing of indium arsenide lattices are similar to those of cuprous arsenide. A lattice spacing mismatch, Nakamura said, causes defects to form in the material.

To test the purity of their sample, the physicists fired photons at the material’s surface using photoluminescence spectroscopy. The material absorbed the photons, causing it to excite its electrons to a higher energy state. That excitation caused the electrons to emit new photons.

By then monitoring the behavior of the emitted light, the team determined that its process successfully generated a single-crystal film without defects. The team said it now plans to combine semiconductors made of different halides to look at the unknown properties that could emerge. Doing so, Nakamura said, will enable the exploration of novel functionalities and physics at the halide interfaces.

The research was published in Applied Physics Letters (www.doi.org/10.1063/5.0036862).

Photonics.com
Apr 2021
GLOSSARY
optoelectronics
A sub-field of photonics that pertains to an electronic device that responds to optical power, emits or modifies optical radiation, or utilizes optical radiation for its internal operation. Any device that functions as an electrical-to-optical or optical-to-electrical transducer. Electro-optic often is used erroneously as a synonym.
epitaxy
A well controlled thin films technique for growing films with good crystal structure in ultra high vacuum environments at very low deposition rates. Epitaxy methods are well known for the growing of single crystals in which chemical reactions produce thin layers of materials whose lattice structures are identical to that of the substrate on which they are deposited. Some examples are molecular beam epitaxy, liquid phase epitaxy and vapor phase epitaxy. Molecular beam epitaxy is also commonly...
Asia PacificResearch & TechnologyRIKENsemiconductorsoptoelectronicsoptoelectronic devicesthin filmsvacuumspectroscopyphotoluminescence spectroscopymaterialsDisplaysConsumerepitaxymolecular beam epitaxy

Comments
LATEST HEADLINES
view all
PHOTONICS MARKETPLACE
Search more than 4000 manufacturers and suppliers of photonics products and services worldwide:

back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2021 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, [email protected]

Photonics Media, Laurin Publishing
x We deliver – right to your inbox. Subscribe FREE to our newsletters.
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.