Wednesday, April 21, 2010

Interpretive Dance and Semiconductor Physics

Greetings! I am beginning this blog to help explain some of the mysteries of technology because it is difficult to keep pace with all of today’s advances. I want to provide an understanding of the esoteric scientific underpinnings that surround our everyday life. I’ll take on hard-hitting topics from nanotechnology and chip fabs to Mentos and Diet Coke. I will try to explain seemingly unrelated topics from Hudsons voyages to the latest lyrics, all from a scientific viewpoint. As humans, we all see the world differently. Scientists see the world as simply reflected electromagnetic radiation with wavelengths between approximately 400 nm and 750 nm. This blog will explain ideas from this point of view without boring you with scientific jargon and long-winded descriptions. It will hopefully be fun, relevant and educational “info”tainment.

For my very first post, I thought it might be useful to explain some of the science behind semiconductors as the Capital Region is arguably becoming a major hub of semiconductor activity. To me, a semiconductor is one of the most misunderstood materials. The mention of the word ‘semiconductor’ often conjures up images of computers; the two always seem to be intertwined. But why? While semiconductors are used in computers, they are also used in LEDs, solar cells, sensors, and zillions of other electronic gadgets.

A scientific explanation of semiconductors involves looking at the electronic band structure and noticing a characteristic band-gap between conduction and valance band. However, explanations like this are tough stuff. As such, I’ve come up with my own analogy to explain semiconductor behavior through interpretive dance. That’s right, interpretive dance. I figure this explanation will stick with you and you can use it at your next cocktail party to look like a genius.

Imagine a stage with a dancer laying motionless on the floor. This motionless dancer is ‘the insulator’. Glass, plastic and ceramics are all traditional insulators because they don’t pass heat or electricity very easily. Now picture a hyper-active dancer jumping all over the stage with a flowing ribbon in tow. This dancer is ‘the conductor’ and simulates the behavior of electrons in a conductor. When most people think of conductors, they think of metals because they conduct electricity and heat very well - that’s why we make frying pans and wires from them. So we have one dancer laying motionless on the stage (‘the insulator’), one dancer leaping across the stage with flowing ribbon (‘the conductor’), and now enters ‘the semiconductor’ as a third dancer. Picture a dancer, motionless on the floor like ‘the insulator’, until a laser spotlight shines on her and she starts leaping around like ‘the conductor’. Once the laser spotlight moves away from her, she falls motionless to the floor again. She remains motionless until the laser shines upon her to excite her once more into dancing. This is ‘The Dance of the Semiconductor’. A semiconductor is inherently an insulator but can be made into a conductor given a stimulation; hence the name ‘semi’ conductor. The stimulation can come as an applied voltage, as heat, or in this case via laser excitation.

Which is what makes a semiconductor such an interesting material; they conduct like wire but without stimulation revert back to being an insulator. Because of this ability, they make really good on-off switches. A fancy version of an on-off switch is called a transistor, one of the key building blocks for computer logic which is why people map semiconductor materials to computers. Now, however, we have learned ‘The Dance of the Semiconductor’ and understand this “Dancing Queen” can be used in many ways. I think ABBA summed up the potential of semiconductors best, “See that girl, watch that scene, dig in the dancing queen”.

There are several resources online that explain more about semiconductor applications:

and my favorite site which explains nano-sized semiconductor particles:

Full-Disclosure, I’m the founder and CEO of Evident Technologies so I’m a bit biased.

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