The ability to remove even the thinnest layers from ‘relatively’ thick and rigid crystals used in semiconductors will lead to more efficient thermal characteristics; lightweight stackability; and greater flexibility. These are key characteristics for a new generation of electronic devices, as well as providing the basis for improvements to solar panels. This type of technology will appeal to a number of major companies.
This is the process that technology giant IBM have been working on. The business and computing leader has been developing a method termed “controlled spalling”. This is a type of layer transfer technique has been tested out with gallium nitride crystals. These crystals are commonly used as a semiconductor material (they are commonly used in light-emitting diodes; the crystals also have special properties for applications in optoelectronic devices). The new method has successfully created a pathway for producing many layers from a single substrate. This was achieved without triggering crystalline damage.
The technique can be fine-tuned to create variations with strain-induced optical effects and fracture toughness. A thinner structure also provides advantages of lower electrical resistance and the heat generated is easier to remove.
In terms of applications the main focus is with optoelectronics. This refers to the study and application of electronic devices and systems that source, detect and control light, usually considered a sub-field of photonics. An example is with photodiodes, which are semiconductor devices that converts light into an electrical current. These are found in, for instance, with solar cells. With future electronics the ultrathin structure will help develop the concept of the spray on solar cell. This is being looked at by big players in the solar market, like Panasonic, Fujifilm, Statoil ASA and Legal & General Capital; each player is starting to invest heavily in this technology.
READ MORE: Why spray-on solar cells will be good for business
Commenting on the research, Stephen W. Bedell of IBM told Controlled Environments: “Our approach to thin film removal is intriguing because it’s based on fracture.” He explains that the process involves depositing a nickel layer onto the surface of the material that requires removal. After this a layer of tape is rolled onto the nickel and tape is then peeled away. The stressed nickel layer produces a crack in the underlying material. This goes down into the substrate and then travels parallel to the surface. This process, seemingly simple, will lead to new types of high-power, high-voltage electronics.
The IBM development has been reported to the Journal of Applied Physics. The research paper is titled “Layer transfer of bulk gallium nitride by controlled spalling.”
