Public Release: 

The superhero semiconductor: Inflexible during the day, but bendy at night

American Association for the Advancement of Science

Scientists have discovered that a type of inorganic semiconductor, which doesn't deform well under light, can bend a whopping 45% from its original form when in the dark. Due to their brittleness, inorganic semiconducting materials tend to fail when subjected to external forces. Yet, easily shapeable, strong, and tough inorganic semiconductors are needed in a variety of electronic applications. Yu Oshima and colleagues were studying the deformation of zinc sulfide crystals under different light conditions: white light, ultraviolet light, and in complete darkness. Microscopy showed that, under the two light conditions, the inorganic semiconducting material immediately cracked when the researchers attempted to deform it, as would be expected; in contrast, the zinc sulfide could withstand substantial deformation, up to 45%, when in complete darkness. The reason for this difference relates to the nature of the defects that occur in zinc sulfide crystals during deformation. Along the cores of these defects, light causes electrons and holes to be trapped at extra energy levels; the resulting motion from this energy and entrapment causes fracturing. In the safety of darkness, electrons do not get trapped in such a way, allowing the material to deform and return to its original configuration.

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