Photodiodes based on nanotubes surpassed analogues

Researchers from the National Institute for Nanotechnology (Canada), Cornell and Michigan State University (both - the USA) have designed photodiodes based on nanotubes, which are markedly superior to existing analogues on the conversion efficiency energii.V their experiments the authors used single-walled carbon nanotube length 3-4 mm and a diameter of 1 ,5-3, 6 nm, which were placed on substrates of complex structure. The silicon substrates served as the bottom layer closure on top of it a layer of silicon dioxide thickness of 100 nm, and then - molybdenum controlling electrodes 50 nm thick, which are covered by another layer of silicon dioxide. Contacts for nanotubes were made of gold and hroma.Pri a voltage bias device functioned as a photodiode. To determine the characteristics of the photodiode investigators sent to the nanotube, laser, they said, with a substantial reverse bias and temperature below 90 to begin the process of shock excitation (ie, getting a photon leads to the formation of multiple electron-hole pairs). Increasing the bias voltage led to a stepwise increase of photocurrent, raising the energy of photons, the researchers were able to increase the scope of "steps". "Characteristics of the process say that nearly all the excess energy of a photon takes to get extra electrons - marks one of the authors Geybor Nathan (Nathan Gabor). - It is extremely important because the main disadvantage of solar cells are just lost in the conversion of energy. "However, to develop the industrial production of such devices in the near future is likely to fail. "We have only studied the physics of the process and proved that it is possible", - concludes Mr. Geybor.