Room temperature electroluminescence from metal oxide-silicon surface-barrier diode

Room temperature electroluminescence (EL) corresponding to silicon band gap energy is observed from ITO-nSi surface-barrier diodes fabricated by a spray pyrolysis technique, where ITO is a transparent conducting film of tin-doped indium oxide. This film is separated from silicon by a thin interfacial SiO_x layer about of 10 Å thick grown on the silicon surface in hydrogen peroxide solution. The work functions of ITO and Si are such that surface n-type silicon layer is inverted to p type, and induced a p⁺-n junction is formed at the surface of the silicon. The tunneling current through SiO_x layer provides an ohmic contact between ITO and surface-induced p-Si layer. Distinction of investigated structures is a significant minority-carrier injection ratio about 0.35 determined from examination of ITO-nSi-ITO transistor behavior. The injection ratio can reach the value of 0.8 when the potential barrier height on Si surface is 0.9 eV. High-efficiency EL was investigated under excitation with forward biased short (10-200 μs) current pulses up to 500 A/cm². Spectral dependence of EL is connected with radiative recombination of injected electron-hole plasma.