Silicon, the long time material of choice for the semiconductor industry, is now facing some competition. Engineers are exploring new compounds for use as the basic building blocks in the computer chips of tomorrow.

If advances in the semiconductor’s structure are to continue beyond the next decade, it’s likely that they will be made using other materials in addition to silicon. This is largely due to the limitations designers will face in the number of circuits they will be able to fit onto the material. As it’s written in the Semiconductor Industry Association’s latest Technology Roadmap for Semiconductors: “…new materials can be introduced in the basic superconductor structure to replace and/or augment the existing one to further extend the device scaling approach.”

While silicon will continue to play the star role in superconductor manufacturing, other compounds are being explored for the additional properties they can bring to the structure. This search is spurred by the fact that semiconductors are built by laying the materials atop an existing semiconductor crystal, making the combination of materials relatively easy. The use of silicon as a primary building material for superconductors will remain optimal for the computer industry. It is the emerging niche markets, such as wireless devices and night vision products, that are demanding different semiconductor properties and thus, different materials. Those currently being tested for these applications include silicon germanium (SiGe), a combination of silicon (Si) and germanium (Ge); indium phosphide (InP); gallium arsenide (GaAs) and a host of newly minted organic compounds that have carbon as their base element.

Out of the new wave of semiconductor compounds, silicon germanium (SiGe) is probably traditional silicon’s biggest competition. Even so, it is unlikely the compound will replace silicon anytime soon. Those who have adopted it, however, cite its advantages as its high performance, low noise level and affordable cost which puts it economically in the same range as silicon. Silicon germanium is chiefly being groomed for use in wireless devices. If the proponents of BlueTooth, the new wireless device communications protocol, have their way, wireless web devices will be as commonplace as cell phones in a matter of years. A scenario that will mean enormous market opportunities for silicon germanium.

Indium phosphide (InP) holds promise as material for semiconductors in both digital and radio-frequency applications. This compound’s advantage is that it can emit and detect light at frequencies that are far out of the range of traditional silicon semiconductors. This ability makes them ideal for applications involving advanced fiber optics. Unfortunately, problems with yield and reliability, referring to the shelf life of the material before it deteriorates, not to mention the relative fragility of the substance, may cut the hamstrings of Indium phosphide before it can prove itself in the semiconductor field. Another drawback is the steep cost of this material.

Cost-wise and performance-wise, gallium arsenide (GaAs) is somewhere between silicon germanium on the low-end and indium phosphide on the high-end. Because of this, Gallium arsenide is a good position to be the material of choice for cellular applications in the next few years. In addition, gallium arsenide is being considered for use in cable TV applications, cable modems, satellite communications and “intelligent” cruise control, an application that uses radar to adjust a vehicle’s distance from the objects in front of it.

Finally, a very new and exciting possibility being explored is the use of organic compounds. Scientists have only scratched the surface of what these materials have to offer. The semiconductors that have been manufactured from organic compounds are free of silicon or any inorganic material. They are of a completely organic nature and it would not be incorrect to label them as polymers. Because of this startling departure from traditional semiconductor manufacturing, there is no crystal that needs to be grown. The organic semiconductors can be built on plastic, an improvement that significantly lessens their cost. They are also easier to use when building integrated circuits since they are compatible with all other substrates. Thus far, the main use of organic semiconductors has been in the field of light emitting diode (LED) displays. The material provides LED with greater brightness as well as a host of properties that other semiconductors cannot, such as the ability to be used in flexible displays.

Where these new materials lead the semiconductor industry remains to be seen. One thing is for certain, the semiconductor industry continues to change. More applications are being developed that require semiconductors and the industry is tinkering with these building blocks of technology to meet their needs. By combining elements with a diversity of electrical properties, semiconductor engineers are determining the performance of the technology that is to come.

Source: Brave, new non-silicon world
Alan Radding
Electronic Business, February 2001
http://www.eb-mag.com/eb-mag/Issues/2001/200102/010203brave1.asp