The analysis of Fowler-Nordheim tunneling data in metal-oxide-silicon structures is reviewed. It is concluded that a parabolic dispersion relation for SiO2 and an electron effective mass of mox = 0.5m provide the best description of the experimental results, this conclusion is consistent with recent band structure calculations for SiO2. Also included is a brief discussion of the transverse momentum conservation issue for tunneling from silicon of 〈100〉, 〈110〉, and 〈111〉 orientation into SiO2.

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Optical transmissionand photoconductivity spectra (7 -14 eV) and the field dependence of photoconductivity are presented for thermally grown (amorphous) SiO, films. It is argued that the clearest experimental determination of the band gap in SiO, can be obtained from the field dependence of photoconductivity and its similarity to internal photoemission; a band gap of 9.3 eV for amorphous SiO, is deduced from the data. In view of this result some recent experimental band-gap determinations are criticized and the literature on this subject is examined. The transmission experiments were performed on thin thermally grown (amorphous) SiO, films (450 -5000 A) produced by etching off the silicon substrate and using a fabrication method which is described in detail. The photoconductivity measurements were performed on Al-SiO, -Si structures (SiO, : 600-3500 A). Diode experiments for detecting photoluminescence and possibly excitons are also described. The upper limit on photoluminescence yield was determined as -10 ".

A study has been made of high-field electronic transport in thermally grown SiO2 in which the injection and transport of carriers were induced by charging the exposed surface of the insulator with ions extracted from a corona discharge. This technique totally avoids destructive breakdown through weak spots in the insulator. Auxiliary developments included a comparison technique for measuring the steady-state potential difference across the unmetallized insulator and a p-n junction method for determining the sign of the principal charge carrier in the oxide. Using a corona discharge in dry air, breakdown fields of approximately 6.5 and 13.5 MV/cm were obtained for charging with positive and negative ions, respectively. Electrons were identified as the current carriers for both polarities of applied field. Measurements of the discharge of the samples, made with a Kelvin probe, yield results that are consistent with Fowler-Nordheim tunneling of electrons from the silicon into the oxide, with an electron effective mass in the oxide m*ox=0.48m. Positive charge accumulation was observed in the oxide after charging with negative corona to fields above 11 MV/cm.

Two experimental observations are reported concerning the degradation of the Si–SiO2 interface during electron injection in metal-oxide-semiconductor structures. First, the generation of the interfacial positive charge during avalanche injection can be strongly inhibited by employing magnesium, instead of aluminum, as gate metal, or enhanced by employing gold. This correlates with the different work functions of the metals. Second, during negative bias high-field injection in Al-gate capacitors with thin oxides (≲100 Å), a threshold in gate voltage, of 7–8 V, is found for the generation of the positive charge. Both observations are consistent with a model which assumes that holes generated in the anode by hot electrons, via emission of surface plasmons, are injected into the SiO2 and are subsequently trapped at the Si–SiO2 interface. Other possible mechanisms are also discussed.

Transport measurements were performed on thin films of Si3N4 deposited on Si using carrier injection from low-energy corona ions and a shallow junction detector. Large hole conduction is found for both corona polarities. Examination of the electronic structure of Si3N4 by x-ray photoemission spectroscopy (XPS or ESCA) reveals one broad structure 10 eV wide (FWHM) at the top of the valence bands which results from the bonding of the Si 3s, Si 3p, and N 2p orbitals. This finding is consistent with the hole conduction we observe. The XPS results are compared with those from amorphous SiO2. The tops of the valence band of Si3N4 and SiO2 are found to lie 1.5±0.2 eV and 4.5±0.2 eV, respectively, below the Fermi level of a thin overlayer of gold.

The location of positive trapped charge in the dry thermally grown films of SiO2 on Si in MOS structures has been investigated by combining the internal photoemission-voltage dependence from both interfaces with the capacitance-voltage technique. Trapped holes have been produced in the SiO2 by vacuum ultraviolet (vuv) photons, x rays, and high-field stressing. After irradiation under positive gate bias, trapped holes have been found to reside near the Si-SiO2 interface with an upper limit of about 50 Å determined for their centroid from this interface. After irradiation under negative bias, a similar situation was found to occur near the Al-SiO2 interface; and in addition some positive charge was found approximately at the Si-SiO2 interface. After high-field stressing under negative bias, positive charge was found approximately at the Si-SiO2 interface. The charge locating technique is described in detail as well as the implications of the results to radiation damage and insulator breakdown.

Fowler-Nordheim tunneling at SiO2/4H-SiC interfaces in metal-oxide-semiconductor field effect transistors Appl. Phys. Lett. 105, 142108 (2014); 10.1063/1.4898009Effect of hydrogen annealing on secondharmonic generation from SiO2/Si(111) interfaces J.