Temperature-dependent Fowler–Nordheim tunneling and a compensation effect in anodized Al-Al2O3-Au diodes

Current-voltage

(I - V)

curves of

Al - {Al}_{2} O_{3} - Au

diodes with anodized

{Al}_{2} O_{3}

thicknesses between 12 and

54 nm

have been measured between 100 and

320 K

. Diodes are rectifying at

300 K

. There is a marked decrease in rectification of

I - V

curves as temperature decreases from

300 to 100 K

. Part of the decrease is due to a decrease in current when Au is positive (applied voltage

V_{A} > 0 V

); part of the decrease is due to an increase in current for

V_{A} < 0 V

as temperature decreases. A reversal of the rectification direction has been observed at

100 K

I - V

curves for increasing

V_{A} > 0 V

are affected by the polarization of the diode by a negative voltage.

I - V

curves for decreasing

V_{A}

are independent of previous history and are due to Fowler–Nordheim tunneling,

J = C F^{2} \exp (- B ∕ F)

. Values of

B

and

C

are temperature dependent.

B

is used to obtain an effective barrier height for tunneling,

ϕ_{E}

ϕ_{E}

increases from

\sim 1.5 to \sim 2.5 eV

as temperature decreases from

300 to 100 K

for

V_{A} > 0 V

. For

V_{A} < 0 V

ϕ_{E} \sim 2.3 eV

100 K

and increases to

\sim 2.8 eV

160 K

, except for the diode with

12 nm

{Al}_{2}

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