The electrical characterization of Al/methyl red/p-Si Schottky diode

In this study, [100] oriented and 1-10?cm p-Si crystals have been used. Two different Al/methyl red/p-Si Schottky barrier diodes have been fabricated by adding 2.5x10-3M and 1x10-4M solutions of the non-polymeric organic compound methyl red in chloroform on top of p-Si substrates and then evaporating the solvent. The electronic and interface state density distribution properties were obtained from the current? voltage (I?V) and the capacitance?voltage (C?V) characteristics (high and low frequency) of Al/methyl red/p-Si Schottky barrier diode (SBD) at room temperature. It is seen that both of them show rectifying behaviour. The ideality factors and barrier heights of diodes, prepared with concentrated and diluted organic compound solutions, are calculated by lnI-V graph plots as 1.21, 0.821 eV and 1.45, 0.828 eV, respectively. Their ideality factors and barrier heights are also calculated by surface potential-voltage ( s ? -V) graph plots and found as 1.21, 0.821 eV and 1.45, 0.828 eV, respectively. It is seen that Al/methyl red/p-Si structure prepared with concentrated solution has more rectifying behaviour and it is nearer to ideal diode. It is also seen that for this diode, both results obtained from lnI-V and s ? -V graphs confirm each others. These results are attributed to less oxide thickness of diode prepared with concentrated solution. Energy distributions of interface state densities which were placed interface between organic compound and inorganic semiconductor have been calculated by using high frequency (5MHz) and low frequency (100 kHz) capacitance for both diodes. These distributions for concentrated and diluted diodes have been found between (0.675- EV)eV and (0.783-EV)eV and between (0.699-EV)eV and (0.791-EV)eV, respectively. In addition, interface state densities, Nss, for concentrated and diluted diode have been found between 3.605x1013cm-2eV-1 (for (0.675-EV)eV) and 2.542x1012cm-2eV?1 (for (0.783-EV) eV), and between 4.162x1012cm-2eV?1 (for (0.697- EV)eV) and 1.699x1012cm-2eV?1 (for (0.791-EV) eV), respectively. The interface state densities have exponential rises with bias from the mid-gap towards the top of the valence band.