Influence of semiconductor barrier tunneling on the current-voltage characteristics of tunnel metal-oxide-semiconductor diodes

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Abstract
Current–voltage characteristics have been examined for Al–SiO2–pSi diodes with an interfacial oxide thickness of δ≊20 Å. The diodes were fabricated on 〈100〉 and 〈111〉 oriented substrates with an impurity concentration in the range of NA=1014–1016 cm−3. The results show that for low forward voltages, the diode current is increased with increased NA, but for higher forward voltages, the diode current is decreased as NA is increased. For the diodes examined in this work, the results presented lead to the conclusion that the diode current should be treated as a superposition of multistep tunneling recombination current and injected minority carrier diffusion current. This can explain the observed values of the diode quality factor n. The results also show that the voltage drop across the oxide Vox is increased with increased NA, with the result that the lowering of the minority carrier diode current Jmin is greater than in the usual theory. The conclusion drawn is that the increase in Vox and lowering of Jmin is due to multistep tunneling of majority carriers through the semiconductor barrier.