Optically Driven Tunable Transistor Effect at Matter/Vacuum Interface—Toward Dielectric Optical Transistors

The laser controlled transistor effect at the dielectric/vacuum interface characterized by tunable current–voltage characteristics was studied in this work. An Yb3Al5O12 nanoceramic was used as the dielectric substrate. It was shown that continuous wave near-infrared (975 nm) laser excitation is able to induce effective charge accumulation in the Yb3Al5O12/vacuum interface region. The accumulated charge may further be freely transported in the vacuum channel between the electrodes. The observed effect was discussed in terms of electric field enhanced thermionic electrons emission from nanoscale objects. Such electron release from nanoscale objects is seen to be strictly related to the nanoparticle’s surface, including exposure of a number of broken bonds which are associated with a large charge state that cannot be easily compensated under vacuum conditions. Performed experiments revealed that the laser-induced charge accumulation effect is a nonlinear process characterized by a threshold point of ca. 0.8 W/mm2 for λ = 975 nm of optical density. The investigated device was characterized by a very large relative current gain (105) and tunable output characteristics. It was also shown that the output characteristic for such a dielectric transistor may be freely tuned from fully symmetric to asymmetric blocking, which is characteristic for rectification behavior of the classical p–n junction. Due to the dielectric properties, free space propagation of the gate signal, and high mobility of nearly free electrons, this kind of transistor may be seen to be used for special applications involving hazardous environments, very fast switching, vacuum conditions (cosmic space), or high voltage switching where galvanic isolation of the gate electrode is of high importance.