02/10/2012

University of Illinois at Urbana-Champaign

New technique makes it easier to etch semiconductors

Creating semiconductor structures for high-end optoelectronic devices just got easier, thanks to University of Illinois researchers.

The team developed a method to chemically etch patterned arrays in the semiconductor gallium arsenide, used in solar cells, lasers, light emitting diodes (LEDs), field effect transistors (FETs), capacitors and sensors. Led by electrical and computer engineering professor Xiuling Li, the researchers describe their technique in the journal Nano Letters.


A semiconductor's physical properties can vary depending on its structure, so semiconductor wafers are etched into structures that tune their electrical and optical properties and connectivity before they are assembled into chips.

Semiconductors are commonly etched with two techniques: "Wet" etching uses a chemical solution to erode the semiconductor in all directions, while "dry" etching uses a directed beam of ions to bombard the surface, carving out a directed pattern. Such patterns are required for high-aspect-ratio nanostructures, or tiny shapes that have a large ratio of height to width. High-aspect-ratio structures are essential to many high-end optoelectronic device applications.

While silicon is the most ubiquitous material in semiconductor devices, materials in the III-V (pronounced three-five) group are more efficient in optoelectronic applications, such as solar cells or lasers.

Unfortunately, these materials can be difficult to dry etch, as the high-energy ion blasts damage the semiconductor's surface. III-V semiconductors are especially susceptible to damage.

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