The Energy Band Diagram

Figure 21. The energy band diagram (only the conduction band is shown) calculated for the silicon/electrolyte interface with a potential drop of 5 V and different radii of curvature. Ec is the conduction bandedge in the bulk and Ecs is the conduction bandedge at the surface. AE AEj, AE1/2, and AE1/5 are the possible tunneling energy ranges for different radii of curvature. The distribution of occupied states at the interface, Dred, is also schematically indicated. After Zhang.24...

The energy band diagram for Ti02 in pH 7 solution is shown in Fig. 2.7. As shown, the redox potential for photogenerated holes is +2.53 V vs. the standard hydrogen electrode (SHE). After reaction with water, these holes can produce hydroxyl radicals ( OH), whose redox potential is only slightly decreased. Both are more positive than that for ozone. The redox potential for conduction band... 

The energy band diagram in the range of n-type region 15 and the p-type layer 12 is shown above. Carriers excited by the infrared ray of 10 microns wavelength band below the electrode 19 are detected at a region between the electrode 10 and the common electrode 17. 

Lacking a detailed theoretical model of how the enhancement of the absorption process should be treated in relation to the energy band diagram, the enhancement will be treated as a multiplier to the underlying dipole-molecular absorption in the spectral region of enhancement. This multiplication factor can be quite large relative to one. 

The energy band diagram for open-circuit condition, where Jr — 0, is assumed to have a configuration shown in Fig. 2a and for the short-circuit condition the configuration is shown in Fig. 2b. An equivalent circuit for this model is shown in Fig. 3. 

FIGURE 1.1. The energy band diagram for a semiconductor showing the lower edge of the conduction band ( d, a donor level and an acceptor level within the forbidden gap (Eg), the Fermi level (Ep), and the top of the valence band ( ,). 

In order to find out whether a semiconductor is liable to electrolytic or corrosion decomposition in any particular system, let us consider the energy-band diagram which plots the electrochemical potential levels for the decomposition reactions (39a) and (39b). 

Instead of plotting the electron distribution function in the energy band diagram, it is eonvenient to indieate the position of the Fermi level. In a semieonductor of high purity, the Fermi level is elose to mid-gap. In p type (n type) semiconductors, it lies near the VB (CB). In very heavily doped semiconductors the Fermi level ean move into either the CB or VB, depending on the doping type. 

Optical characteristics and the energy band diagram of CuPc and BPPC. (a) Absorption spectra of CuPc and BPPC for vacuum deposited device and (b) energy band diagram of the single heterostructured CuPc and BPPC OPD. 

In most metal-semiconductor contacts, the semiconductor surface before metal deposition is prepared by chemical cleaning and a thin insulating oxide layer is invariably left on the surface of the semiconductor. The thickness of this interfacial layer depends on the method of surface preparation and, for a good Schottky contact, must be less than about 20A. The energy-band diagram of a contact with an interfacial oxide layer is... 

In (b) and (c) the corresponding changes of the energy band diagram and the l/V characteristics following hydrogen exposure (black) are given. 

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