Injected carriers

The distributions of excess, or injected, carriers are indicated in band diagrams by so-called quasi-Fenni levels for electrons or holes (Afp). These functions describe steady state concentrations of excess carriers in the same fonn as the equilibrium concentration. In equilibrium we have... 

The enormous progress in the field of electroluminescent conjugated polymers has led to performances of oiganic light-emitting devices (LEDs) that are comparable and in some aspects superior to their inorganic counterparts 11). Quantum efficiencies in excess of 5% have been demonstrated [2] and show that a high fraction of the injected carriers in a polymeric electroluminescence (EL) device form electronic excitations which recombine radiatively. 

An efficient LED has two essential characteristics (1) all of the injected carriers recombine in the device and (2) the operating voltage is as low as possible. To produce light efficiently, all of the current should lead to recombination. This... 

Important electrical informations about OLEDs, such as charge transport, charge injection, carrier mobility, etc., can be obtained from bias-dependent impedance spectroscopy, which in turn provides insight into the operating mechanisms of the OLED [14,15,73,75 78]. Campbell et al. reported electrical measurements of a PLED with a 50-nm-thick emissive layer [75], Marai et al. studied electrical measurement of capacitance-voltage and impedance frequency of ITO/l,4-Mv-(9-anthrylvinyl)-benzene/Al OLED under different bias voltage conditions [76], They found that the current is space-charge limited with traps and the conductivity exhibits power-law frequency dependence. 

When using the continuous flow method, however, some additional versatility is available in chemisorption measurements. For example, when data is required at an adsorbate pressure of 0.1 atm, a 10 % mixture of adsorbate, mixed with an inert carrier gas, is passed through the apparatus with the sample cooled to a temperature at which no chemisorption can occur. Upon warming the sample to the required temperature, adsorption occurs producing an adsorbate-deficient peak that is calibrated by injecting carrier gas into the flow stream. Equation (15.9) is then used to calculate the quantity adsorbed. This process is repeated for each concentration required. Caution must be exercised to avoid physical adsorption when the sample is cooled to prevent chemisorption. Should this occur, the adsorption peak due to chemisorption can be obscured by the desorption peak of physically bound adsorbate when the sample is heated. 

Sesame Sesamum indicum (Pedaliaceae) seed 44-54 oleic (35-50), linoleic (35-50), palmitic (7-12), stearic (4-6) food oil, soaps, solvent for injections, carrier oil (aromatherapy)... 

The operation of the SPICE design is closely analogous to that of a conventional bipolar transistor comprising distinct emitter, base, and collector stages but with some differences that are forced by materials considerations. The central base layer is a doped semiconductor and in it is established a non-equilibrium minority carrier population by injection from the emitter. Additionally these injected carriers are partly spin polarized and when they are harvested by the spin-dependent collector, the collection efficiency is dependent on the relative orientations of the emitter and collector orientations. The feasibility of these devices depend on several issues,... 

FIGURE 1 The maximum gain of GaN and GaAs as a function of injected carrier density. 

Shallow Traps. In the presence of traps, the nm mobile and nt trapped carriers contribute to the space charge. Shallow traps mean that the delay time in the trap is considerably shorter than the transit time of the injected carriers. Under these conditions, Child s law (5.3) remains valid, if an effective mobility peft = s used instead, weighted by the percentage of mobile carriers 6 = nm/(nm + nt). 

---