Electronic hole current

Figure 13-11. (a) A diagram showing ihc spatial distribution of lire relative hole and electron currents in an OLED. The recombination efficiency h is equal to the fraction of the electron (hole) current that docs not make it to the anode (cathode) (b) cll icicncy-currcni balance diagram for OLEDs. Sec text for details. 

Fig. 8-13. Electron transfer via the conduction band and hole transfer via the valence band >ox (Dveo) = state density of oxidant (reductant) particles x - distance from an interface i ( ) = anodic (cathodic) current in (ip) = electron (hole) current.

Fig. 6. Electron-hole currents at a semiconductor-electrolyte interface (a) and their dependence on the change of potential drop in the semiconductor (b) 1—i , 2—i , 3—ip,...

Illumination of a semiconductor, leading to a change of the charge-carrier concentration in the bands, also affects, according to Eqs. (23) and (24), the electron-hole currents. It is this effect that underlies a specific behavior of semiconductor electrodes under illumination. Obviously, illumination affects most strongly the current of minority carriers, whose relative concentration may vary especially noticeably. 

The Qi Zj positive electron holes required for this reaction are provided by the electron-hole current through layer 1, again in accord with the coupled-currents condition for single-phase growth. 

Therefore the measurement of a chemical shift value on a designing of new materials helps to evaluate of their doping efficiency. It is applied to increase of the electronic (hole) current carriers density. 

Here, as usual, i,f are the widths of the initial and final electron states and is averaged over initial states and summed over the final states the square modulus of the Hamiltonian of the electron hole current-nuclear current interaction. It can be written (Mj-K transition) as follows (see details in Ref. [23]) ... 

Methods of measurement to be applied to MIECs should distingiush between the overpotential for electron/hole current and the overpotential for ion current. 

Amorphous Silicon. Amorphous alloys made of thin films of hydrogenated siUcon (a-Si H) are an alternative to crystalline siUcon devices. Amorphous siUcon ahoy devices have demonstrated smah-area laboratory device efficiencies above 13%, but a-Si H materials exhibit an inherent dynamic effect cahed the Staebler-Wronski effect in which electron—hole recombination, via photogeneration or junction currents, creates electricahy active defects that reduce the light-to-electricity efficiency of a-Si H devices. Quasi-steady-state efficiencies are typicahy reached outdoors after a few weeks of exposure as photoinduced defect generation is balanced by thermally activated defect annihilation. Commercial single-junction devices have initial efficiencies of ca 7.5%, photoinduced losses of ca 20 rel %, and stabilized efficiencies of ca 6%. These stabilized efficiencies are approximately half those of commercial crystalline shicon PV modules. In the future, initial module efficiencies up to 12.5% and photoinduced losses of ca 10 rel % are projected, suggesting stabilized module aperture-area efficiencies above 11%. 

The electrical characteristics of ceramic materials vary gteady, since the atomic processes ate different for the various conduction modes. The transport of current may be because of the motion of electrons, electron holes, or ions. Electrical ceramics ate commonly used in special situations where reftactoriness or chemical resistance ate needed, or where other environmental effects ate severe (see Refractories). Thus it is also important to understand the effects of temperature, chemical additives, gas-phase equilibration, and interfacial reactions. 

E = dV/dx defined as V/m. The ions and electrons reestablish equilibrium by moving in the field which results in a net electric current density j defined as C/(m -s) or A/m. An electron or an electron hole has a unit charge, e = 1.601 x 10 C an ion has this unit charge times its valence Thus the... 

The hole current in this LED is space charge limited and the electron current is contact limited. There are many more holes than electrons in the device and all of the injected electrons recombine in the device. The measured external quantum efficiency of the device is about 0.5% al a current density of 0.1 A/cm. The recombination current calculated from the device model is in reasonable agreement with the observed quantum efficiency. The quantum efficiency of this device is limited by the asymmetric charge injection. Most of the injected holes traverse the structure without recombining because there are few electrons available to form excilons. 

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