Credit: Image courtesy of Lawrence Berkeley National Laboratory
Semiconducting films are grown on different substrates at high temperatures and then rapidly cooled to induce deformation. This process can be used to controllably modify the films’ electronic properties. If the substrate (blue) contracts the same as the semiconductor film, then the material is not stretched or compressed (referred to as having “no strain”). When the substrate (green) contracts more, the 2-D material is compressed. When the substrate (red) contracts less, the semiconductor is stretched. Stretching leads to a change in the electronic properties of the film and significantly improves its photoluminescence efficiency, which is important for developing high-efficiency lights and lasers.