Applications of nanocrystalline metal oxide films in monocrystalline silicon light emitting diodes

摘要

Room temperature electroluminescence (EL) corresponding to the silicon band gap energy was observed from ITO-nSi surface-barrier diodes fabricated by a spray pyrolysis technique, where ITO is a transparent conducting nanocrystalline film of tin-doped indium oxide. This film is separated from silicon by a thin interfacial SiO_x layer of about 1 nm thick grown on the silicon surface using a hydrogen peroxide solution. It is shown that an induced p-n junction is formed at the surface of the silicon. The tunneling current through the SiO_x layer provides an ohmic contact between the ITO and the surface-induced p-Si layer. A distinction of the investigated structures is a significant minority-carrier injection ratio of about 0.35 determined from the examination of the ITO-nSi-ITO transistor behavior. The injection ratio can reach the value of 0.8 when the potential barrier height on the Si surface is 0.9 eV. High-efficiency EL was investigated under an excitation with short current pulses (10-200 μs) up to 50 A. Spectral dependence of EL is connected with the radiative recombination of injected electron-hole plasma.