Nanowire transistors: going nowhere fast

In the race to scale transistors down to the smallest possible size, the relevant research attracts a lot of money and hype. Unfortunately, the hype often obscures the real nature of any breakthroughs and completely ignores the unsolved problems associated with the technology. This time, it is the turn of nanowires to get over-hyped. Nanowires hold the promise of creating transistors and diodes on a very small scale simply by joining wires together. 老域名购买

Unfortunately, there are a few stumbling blocks in the way, which are best explained by taking a quick look at how a normal transistor is put together. Normal semiconductors work by making alternating layers of materials that have an excess of electrons and materials that have a deficit of electrons. The interaction between the different layers creates a barrier that can be raised or lowered by changing an applied voltage, which in turn controls the amount of current that can flow through the device. Even though there are other ways to make transistors, the key message is that transistors require two different materials to be joined up in a controlled fashion, with a precise layer thickness.

Research, described in an article published by Nanoletters, demonstrates nanowires with both an excess and a deficit of electrons. This is an important stepping stone towards the development of nanometer scale electronics, but it is not quite the breakthrough advertised because it offers no insight into how to solve the other problems. The transistors manufactured by the collaboration between the University of Washington and Stanford are made by blobbing the two different wires on gold pads and hoping that they stick. As they stick, some wires will bridge the gap between adjacent pads, forming the junction required to make a transistor. The result is that every transistor is made from an unknown number of nanowires, all connected in parallel between two gold pads. This means that the researchers can't control the switching characteristics of the transistors at all. Worse than that, the gold pads must be lithographically patterned, meaning that the total size of the transistor is the same as that for a normal semiconductor.

In short, a nice piece of chemistry that may prove to be useful in the future. However, we will have to wait for an engineering break through to fulfill its promise.

Nanoletters, 2007, DOI: 10.1021/nl071495u

Nanoletters, 2007, DOI: 10.1021/nl0627036