Although it has been previously shown that photoconductive materials saw an increase in their electrical conductivity following the exposure to light, conditions required to create a viable use for it weren’t exactly pleasant. Tests with simple memory storage devices only worked under extreme cooling, suggesting the practical applications were limited.
This latest breakthrough by Washington State University suddenly makes the technology look more viable.
In the test, researchers took an annealed crystal of strontium titanate (STO) and noted that when exposed to light at room temperature, its resistance decreased by three orders of magnitude, and free electron concentration increased by a factor of several hundred (via Nature). In short, it became conductive enough use in electronics.
That improved conductivity was maintained for several days afterwards, even when the crystal was stored in a dark environment.
Taking the experiment a step further, researchers were able to ‘draw’ a path of low resistance on the crystal using a laser beam. That improved conductivity along the ‘circuit’ on the crystal, opens up the possibility for the creation of transparent electronic circuits that could be erased through heating.
Although there was some increase in resistance over successive days, it was marginal, and the light exposure appeared to have a long-term effect on the crystal’s conductivity.
What’s most impressive about this test, is that resistance could be gradually reduced between two points. Exposing the first point to the laser created a noticeable reduction in resistance between the two, but it was only in exposing both of them that resistance really fell. While exposing the path between them had a dramatic effect itself, it was not as effective as exposing the two contact points.
Although this sort of research is still in its very early stages, it shows potential and those behind it believe that it could one day lead to the creation of transparent electronics that could be erased and re-written. If possible, it would offer a rare alternative to silicon.
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