It is reasonable to claim that the electronics revolution began in 1947 with the discovery of the solid state transistor by Bardeen, Brattain, and Shockley at Bell Labs. This led to portable electronics, the integrated circuit, and eventually computer chips. These chips are made on a semiconductor substrate of solid crystal silicon. We have since found ways to create amorphous silicon coatings on large glass substrates to support the transistors that switch the pixels in large displays such as televisions. But with the advent of wearable electronics, designers need circuits on lightweight, flexible substrates.
One approach is to create alternatives to silicon as a backplane material for solid state devices, using printable organic inks and other materials. The problem with silicon is that it requires high processing temperatures that would destroy any paper or plastic substrate used for a flexible device. Until now.
In a story reported in IEEE Spectrum, researchers in the Netherlands have developed a way to create silicon backplanes on paper substrates. The technique starts by coating the paper with liquid polysilane ink, and then hitting the ink with light from an excimer laser. In nanoseconds, the liquid is transformed into crystaline silicon, ideal for creating semiconductor components. This laser annealing process is similar to that used in the display industry to transform low-performing amorphous silicon coatings into higher performing poly-silicon. This new process using paper substrate results in poly-silicon layers with similarly high performance.
This could usher in a new era for solid state electronics, printed inexpensively on paper substrates that would be bio-degradable, but providing performance equivalent to today’s rigid printed circuit boards. This new technology has applications ranging from wearable Health Tech devices to solar cells and smart packaging.
