ELECTRICAL CHARACTERIZATION OF VISIBLE EMITTING ELECTROLUMINESCENT SCHOTTKY DIODES BASED ON N-TYPE POROUS SILICON AND ON HIGHLY DOPED N-TYPE POROUS POLYSILICON

The electrical behaviour of electroluminescent Schottky diodes fabrica ted on the base of aluminum and n-type porous silicon is reported. Por ous silicon was formed by electrochemical etching in HF aqueous soluti ons of n-type monocrystalline silicon and of degenerate n(+)-type poly silicon. The polysilicon layer was formed on monocrystalline silicon s ubstrate by low pressure chemical vapour deposition (LPCVD). The elect roluminescence (EL) starting voltage was in the range 4-20 Volt, depen ding on the doping level of Si substrate; polysilicon samples showed a higher starting voltage. Developed devices showed broad EL spectra, c overing the whole visible range. Electrical measurements include curre nt-voltage characteristics and capacitance-voltage characteristics. Ti me response and stability of the light emitting devices was also measu red, showing excellent speed and reliability characteristics.