Oxide thickness

The effect of the presence of a thin interfacial oxide on the dark current voltage characteristics of an SBSC has been examined in sections 2.2 and for the min MIS cell in 2.5. The exact role of the interfacial oxide is not fully understood at present, although it is known that both minority and majority carrier flow over the barrier decrease with increasing oxide thickness. If the oxide is sufficiently thick so that its transmission coefficient is no longer unity, the reverse saturation current density obtained from the forward vs V, characteristics is reduced causing an increase in the effective barrier height ) This effect is 

The use of interfacial oxides to increase the open circuit voltage and conversion efficiency of SBSCs has been extensively reported The optimum oxide thickness reported, 

To summarise, the interfacial oxide thickness should be such that the maximum values of n and are achieved without significantly reducing These requirements are conflicting and a 

A number of techniques have been used for providing the I layer in the MIS solar cell these have been summarised by Pulfrey and are repeated in Table I below. The standard procedure is to thermally grow a layer of Si02 on the parent substrate. QT he problem however is that for the thin oxide layers required 20 A thick the thermally grown oxides are silicon rich and are not likely to be homogeneous SiOa until a thickness of 50 A is reached. 

INSULATING LAYER GROWTH METHODS USED IN MIS CELLS 

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Si /Si 2p peak areas as a fiinction of take-off angle. The solid line is a fit which corresponds to an oxide thickness of 2.0 mn (from [12]). 

For the manufacture of silicon semiconductor devices, oxide thicknesses of from <10 to >1000 nm are required on sHces of single-crystal silicon. These oxide layers are formed at elevated temperatures, generally at about 1000°C, in an atmosphere of either oxygen or steam. Usually the oxidation is at atmospheric pressure, but sometimes, to speed the oxidation rate, pressures of several atmospheres are used. Oxidation consumes a silicon thickness equal to about 0.4 the thickness of the oxide produced (grown). The thickness of the oxide, V (4) is approximately given by equation 1 ... 

If the oxidizing gas is pure oxygen, and iNi2+ remains approximately constant over the oxide thickness... 

In order to carry out depth profiling with AES, the sputtering rate must be determined. The sputtering rate is usually measured by determining the time required to sputter through a layer of known thickness. Anodized tantalum foils are convenient for this purpose since the oxide thickness can easily be controlled and since the interface between the metal and the oxide is relatively sharp [43]. 

Quantifying the effect of surface roughness or morphology is difficult, however. Surface preparations that provide different degrees of surface roughness also usually produce surfaces that have different oxide thicknesses and mechanical properties, different compositions, or different contaminant levels. The problem of separation of these variables was circumvented in a recent study [52] by using a modified microtome as a micro milling machine to produce repeatable, well-characterized micron-sized patterns on clad 2024-T3 aluminum adherends. Fig. 2 shows the sawtooth profile created by this process. 

Weight gain Oxide thickness (mm) (gm X 10 ) Outer scale Inner zone Mass gain Maximum (gm X 10 ) penetration (mm) ... 

A wide variety of in situ techniques are available for the study of anodic hhns. These include reflectance, eUipsometry, X-ray reflectivity, and SXRD. X-ray reflectivity can be used to study thick surface layers up to 1000 A. The reflectance technique has been used to study oxide growth on metals, and it yields information on oxide thickness, roughness, and stoichiometry. It the only technique that can give information on buried metal-oxide interfaces. It is also possible to get information on duplex or multiple-layer oxide hhns or oxide hhns consisting of layers with different porosity. Films with thicknesses of anywhere from 10 to 1000 A can be studied. XAS can be used to study the chemistry of dilute components such as Cr in passive oxide hhns. 

With such a model, the rate of increase in oxide thickness is determined by the difference between alumina formation, strictly following Faraday s law, and its dissolution, the rate of which should be some function of hydrogen ion concentration at the interface, i.e.,... 

Figure 11 exemplifies experimentally observed dependences of the current density on the imposed voltage at a constant oxide thickness. It is seen that they fit both equations fairly well. Tafel slopes [Eq. (44)] are in the range of 0.4 V cm-1 dec-1. All other... 

Metal Current density (mA/ cm2) Oxide thickness (nm) Electric field strength (V/nm) t+... 

Transient effects in naturally aging samples occur with some delay and are very slow. Nazar and Ahmad274 have observed a slow decrease of A1-A1203-A1 capacitance that was attributed to neutralization of Al3+ cations in the vicinity of the internal boundary and a corresponding increase of the effective oxide thickness. However, the same effect may be due to neutralization of negatively... 

The reflectance is shown in Fig. 11.6a as a function of wavelength for three oxide thicknesses of 80, 100, and 120 nm on silicon. The corresponding intensity... 

Color Tuning with Graded Indium Tin Oxide Thickness.502... 

From the transconductance expressions we see that the first (eq. 15) is linear with Vds and the second (eq. 16) is related to both MOSFET gate voltage Vgs and its threshold voltage Vt- In both cases Cox plays an important role. In fact in order to increase the sensitivity, the gate oxide thickness should be as thin as possible. gm,SAT, according to equation 16, depends on Vt and it is known that Vt depends on Vfb-, the flat band voltage, according to ... 

The transient solution to Eq. 7 will be discussed in the next section. Equation 5 can also be directly integrated to relate the remaining polymer thickness to the time dependent oxide thickness... 

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