Taking the strain

A manufacturing technique could lead to semiconductors being formed in any shape, according to materials scientists at the

. The technique can also enhance the conductive properties of the materials, opening up an array of novel applications.

Graduate Michelle Roberts has been working on the technique, which focuses on managing the strain within a semiconducting material as it is formed. Strain is an important factor for semiconductors, which can be both useful and awkward.

When silicon is placed under strain it conducts electricity faster, which can be used to enhance the processing speed of electronics. However, when semiconductors are built up from layers of alloys, the different sizes of atoms can create strain within the crystalline structure which leads to defects having the opposite effect: they scatter electrons through the crystal and impede conduction.

Roberts has devised a method for making a semiconducting membrane from layers of silicon and a silicon- germanium alloy which, although only tens of nanometres thick, has the same properties as a solid wafer of silicon. He explained that these membranes are flexible, and can be made in a variety of shapes, including flat, tubular and curved, depending on the thicknesses of the layers.