Semiconductors hole mobility

Studies of double carrier injection and transport in insulators and semiconductors (the so called bipolar current problem) date all the way back to the 1950s. A solution that relates to the operation of OLEDs was provided recently by Scott et al. [142], who extended the work of Parmenter and Ruppel [143] to include Lange-vin recombination. In order to obtain an analytic solution, diffusion was ignored and the electron and hole mobilities were taken to be electric field-independent. The current-voltage relation was derived and expressed in terms of two independent boundary conditions, the relative electron contributions to the current at the anode, jJfVj, and at the cathode, JKplJ. 

One has to consider that in Eqs. (9.15)—(9.17) the mobility /t occurs as a parameter. As it will be pointed out below, // shows a characteristic dependence on the applied electric field typical for the type of organic material and for its intrinsic charge transport mechanisms. For the hole mobility, //, Blom et al. obtained a similar log///,( ) const. [E dependency [88, 891 from their device modeling for dialkoxy PPV as it is often observed for organic semiconductors (see below). 

The high electrical conductivity of metals as well as the high electron (and hole) mobility of inorganic covalently bound semiconductors have both been clarified by the band theory [I9, which slates that the discrele energy levels of individual atoms widen in the solid stale into alternatively allowed and forbidden bands. The... 

Assuming that the mobilities are the same in both the intrinsic and extrinsic states, combine your information to solve for the electron and hole mobilities of this substance. Can you tell whether the substance is an n-type of p-type extrinsic semiconductor by looking at the data ... 

Semiconductor Energy Gap (eV) Electron Mobility. ve (cm V ls l) Hole Mobility, v (etirV s-1)... 

Equations (1.194) and (1.195) can be accepted, within reason, because both the chemical equilibrium constants and the hole mobility for semiconductors have an Arrhenius-type temperature dependence. It has been shown, by a least-square fitting of the electrical conductivity data of Maruenda et al. to eqn (1.193), that 85 per cent of the data points are within 1.5 per cent of the calculated values, as shown in Fig. 1.58. This indicates that the model proposed here gives an accurate description of the data. The fitting parameters are listed in Table 1.5. 

In equation 3, ran is the effective mass of the electron, h is the Planck constant divided by 2/rr, and Eg is the band gap. Unlike the free electron mass, the effective mass takes into account the interaction of electrons with the periodic potential of the crystal lattice thus, the effective mass reflects the curvature of the conduction band (5). This curvature of the conduction band with momentum is apparent in Figure 7. Values of effective masses for selected semiconductors are listed in Table I. The different values for the longitudinal and transverse effective masses for the electrons reflect the variation in the curvature of the conduction band minimum with crystal direction. Similarly, the light- and heavy-hole mobilities are due to the different curvatures of the valence band maximum (5, 7). 

Tetradecafluorosexithiophene 428 was considered as a potential n-type semiconductor for FETs for the following reasons sexithiophene is an excellent p-type semiconductor with high hole mobility perfluorination is an effective way to convert a p-type organic semiconductor to a n-type one (01JA4643). The absorption and emission maxima of 428 (421 and 471 nm, respectively) shifted to higher energies relative to those of sexithiophene (435 and 508 nm, respectively). 

CuPc thin films, and the enhanced physical connection between source-drain electrodes and semiconductor channel associated with the PMMA polymer layer, the OFET performance of this bottom-contact device was significantly improved with leakage current being reduced by roughly one order of magnitude and on-state current enhanced by almost one order of magnitude. The hole mobility of this bottom-contact OFET device reached 0.01 cm2 V-1 s 1, which is comparable with that of top-contact device but much higher than that of normal bottom-contact device without polymer layer [45],... 

By introducing Lewis-acid V2O5 thin film between semiconductor and insulator layers, Minagawa et al. fabricated CuPc-based OFETs that can be turned on by positive gate voltage, which showed improved hole mobility in comparison... 

For reasonable functioning of these low cost, low mobility semiconductor solar cells, a considerable amount of the photogenerated chemical potential epc — fv of the electron hole ensemble must be used for carrier transport. An acceptable charge collection may be achieved if the extraction times for electrons and/or holes are smaller than their recombination lifetimes, i.e.,... 

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