Voltage-controlled negative resistance and electroluminescent spectra of Al–Al2O3–Au diodes

Abstract

Dielectric breakdown of metal-insulator-metal ͑MIM͒ diodes can result in the development of voltage-controlled negative resistance ͑VCNR͒ in the current-voltage ͑I-V͒ characteristics. Electroluminescence from the MIM diode appears at the same time as VCNR develops. The spectra of electroluminescence associated with VCNR of Al-Al 2 O 3 -Au diodes with anodic Al 2 O 3 has been measured for photon energies between 1.8 eV, the lowest photon energy the photomultiplier can detect, and 3.4 eV, using narrow-band interference filters. Electroluminescent photons have maximum intensity between 1.8 and 2.4 eV with a peak at ϳ2.2 eV. The voltage threshold for electroluminescence in Al-Al 2 O 3 -Au diodes, V TH , is 1.7 to 2.0 V; it is associated with an impurity band in amorphous Al 2 O 3 . Electrons injected into the impurity band can recombine with radiative centers in Al 2 O 3 or can be emitted into vacuum. The range of values of V TH is the same as the range of values of the barrier height at the Al-Al 2 O 3 interface measured by internal photo emission or by tunneling. The spectral data support a model of conduction and VCNR in a conducting channel. Dielectric breakdown and forming of VCNR introduce positive charge at the Al-Al 2 O 3 interface that results in an Ohmic contact and a high field region in the conducting channel. Electrons injected into Al 2 O 3 when the applied voltage is greater than V TH neutralize positive charge, change the Ohmic contact, and cause a decrease in current with increasing voltage. The radiative centers involved in electroluminescence are also responsible for other forms of luminescence in Al 2 O 3 .

Transport and luminescence phenomena in electroformed silicon nitride-based light emitting diode

“…Therefore, the broken-down devices are mostly discarded and are not considered worth studying. Common symptoms of thin film breakdown may be cited as decreased shunt resistance [1,2], nanocrystallization [3,4], voltage-controlled negative resistance [5], electron emission [6,7], memory effect [8,9] and intense electroluminescence (EL) [10,11], the last one being the main motivation of this work. The breakdown event is usually referred to as electroforming or forming when the final product is of scientific and/or technological importance.…”

Optical microcavities and enhanced electroluminescence from electroformed Al-Al2O3-Ag diodes

“…Measurements on Al-Al 2 O 3 -Au diodes show that there is a broad EL spectrum with photon energies between 1.8 and 4 eV. 13,33 The recombination radiation generates SPPs at the Al-Al 2 O 3 and Al 2 O 3 -Ag interfaces. Contrary to the difficulty of generating SPPs by radiation incident from air, 18,19 there is no problem with matching momentum of generating EL radiation to SPPs since the radiation is incident on Al and Ag from anodic Al 2 O 3 , a medium with n d ffi 1.7.…”

Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

“…35 Considering the voltages applied, ionization and neutralization of the defects via recombination processes should occur during the switching between high and low conduction states. 36 The observation of electroluminescence with a wavelength centered at 475 nm from the diodes during the resistive switching argues against creation and destruction of metal filaments between the electrodes as the source of the resistive switching. 37,38 The electroluminescence also indicates that migration of charged defects may not be necessary to explain the resistive switching.…”