Capacitance-voltage

Fig. 5. NMOS capacitance voltage characteristics where C is the oxide capacitance, A shows low frequency characteristics, and B shows high frequency characteristics. At low frequencies C approaches C for negative voltages (accumulation) and positive voltages (inversion). In the flat-band (FB) condition there is no voltage difference between the semiconductor s surface and bulk. The threshold voltage, Dp for channel formation is the point where the...

Figure 23.5 Build-up of capacitive voltage (TRV) on restrike during contact interruption in a grounded star HT capacitor unit...

Schematic energy level diagrams of a metal/polymer/metal structure before and after the layers are in contact are shown in the top two drawings of Figure 11-6. Before contact, the metals and the polymer have relative energies determined by the metal work functions and the electron affinity and ionization potential of the polymer. After contact there is a built-in electric field in the structure due to the different Schottky energy barriers of the asymmetric metal contacts. Capacitance-voltage measurements demonstrate that the metal/polymer/metal structures are fully depleted and therefore the electric field is constant throughout the bulk of the structure [31, 35]. The built-in potential, Vhh i.e. the product of the constant built-in electric field and the layer thickness may be written...

Parker [55] studied the IN properties of MEH-PPV sandwiched between various low-and high work-function materials. He proposed a model for such photodiodes, where the charge carriers are transported in a rigid band model. Electrons and holes can tunnel into or leave the polymer when the applied field tilts the polymer bands so that the tunnel barriers can be overcome. It must be noted that a rigid band model is only appropriate for very low intrinsic carrier concentrations in MEH-PPV. Capacitance-voltage measurements for these devices indicated an upper limit for the dark carrier concentration of 1014 cm"3. Further measurements of the built in fields of MEH-PPV sandwiched between metal electrodes are in agreement with the results found by Parker. Electro absorption measurements [56, 57] showed that various metals did not introduce interface states in the single-particle gap of the polymer that pins the Schottky contact. Of course this does not imply that the metal and the polymer do not interact [58, 59] but these interactions do not pin the Schottky barrier. 

Capacitance-voltage characteristics of a bare and functionalized EIS structure... 

CAPACITANCE-VOLTAGE CHARACTERISTICS OF A BARE AND FUNCTIONALIZED EIS STRUCTURE... 

The typical shape of a capacitance-voltage (C-V) curve for a p-type EIS structure is given in Fig. 7.4. As can be seen from Fig. 7.4, dependent on the magnitude and polarity of the applied gate voltage, VG, three regions in the C-V curve can be distinguished accumulation, depletion and inversion (an n-type EIS structure shows an identical... 

FIGURE 7.4 Capacitance-voltage (C-V) curve for a bare (unmodified) EIS sensor and EIS sensor with a molecular layer (here, DNA). The presence of the additional molecular layer shifts the C-V curve of the original EIS structure along both the capacitance (AC) and voltage axis (A Vfb). 

The preparation of the FEDs, the experimental set-up and measuring conditions for the detection of DNA immobilization and hybridization as well as for the monitoring of the layer-by-layer adsorption of the polyelectrolyte multilayers are described in detail elsewhere [46-50], The attachment of these charged macromolecules to the FED surfaces has been systematically characterized by means of capacitance-voltage,... 

A. Poghossian, M.H. Abouzar, F. Amberger, D. Mayer, Y. Han, S. Ingebrandt, A. Offenhauser, and M.J. Schoning, Field-effect sensors with charged macromolecules characterisation by capacitance—voltage, constant capacitance, impedance spectroscopy and atomic-force microscopy methods. Biosens. Bioelectron. 22, 2100-2107 (2007). 

Capacitance-voltage (C-V) measurements on Schottky diodes orp-n junctions can provide information similar to that yielded by spreading resistance, namely the net charge density of fixed centers that are ionized in the... 

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. 

Y. Huang, X.D. Chen, S. Fung, C.D. Beling and C.C. Ling, Spatial characterization of a 2 inch GaN wafer by Raman spectroscopy and capacitance-voltage measurements, J. Phys. D Appl. Phys., 37, 2814-2818 (2004). 

Figure 2.2 (a) Capacitance voltage characteristics of an n-type SiC-based capacitor at 400°C with a gate of sputtered Pt. (b) Current voltage characteristics of a Schottky diode at 400°C with a porous Pt gate electrode. 

Sodium contamination and drift effects have traditionally been measured using static bias-temperature stress on metal-oxide-silicon (MOS) capacitors (7). This technique depends upon the perfection of the oxidized silicon interface to permit its use as a sensitive detector of charges induced in the silicon surface as a result of the density and distribution of mobile ions in the oxide above it. To measure the sodium ion barrier properties of another insulator by an analogous procedure, oxidized silicon samples would be coated with the film in question, a measured amount of sodium contamination would be placed on the surface, and a top electrode would be affixed to attempt to drift the sodium through the film with an applied dc bias voltage. Resulting inward motion of the sodium would be sensed by shifts in the MOS capacitance-voltage characteristic. 

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