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

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 SiOx 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 SiOx 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. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)