ZnO nanowire LED has ultralow driven current
Zinc oxide (ZnO) is an interesting optical semiconductor that is potentially useful for short-wavelength LEDs (as well as photodetectors).
Zinc oxide (ZnO) is an interesting optical semiconductor that is potentially useful for short-wavelength LEDs (as well as photodetectors). It is unusual in that its normal use is not as a single-crystalline layer, but instead as nanostructures such as nanowires and nanoflakes, used either singly or in sheets. Researchers at the Chinese Academy of Sciences (Changchun and Beijing, China), Jilin University (Changchun, China), and Northeast Normal University (Changchun, China) are creating deep-blue-emitting LEDs that, in some versions, have a polymer intrinsic layer; the devices exhibit a low driven current with a microampere amplitude.
Two types of LED were created: One had a magnesium oxide (MgO) intrinsic layer and a ZnO layer containing vertically aligned ZnO nanowires, while the other had polymer as the intrinsic layer and a ZnO layer with randomly oriented nanowires (both had nanowires with 300 nm diameters). The polymer-containing version had better carrier-blocking ability, resulting in less emission outside the intended 400 nm region. In addition, the 330 μA forward injection current for the polymer version was far lower than the 5.04 mA forward injection current for the MgO-containing version.
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