Charge bias

Step 4 Transfer. Paper is passed between the drum and the transfer corona, which has a polarity that is the opposite of the charge on the toner. The toner image is transferred by a combination of pressure and electrostatic attraction from the drum to the paper. On many color and high-speed machines, it is common to replace the transfer corona with one or more charged bias transfer rollers (BTRs), which apply greater pressure and a higher quality image. 

Fig. 12. Rendition of depth of oxidation-induced shift in bands and core levels for alumina due to space charge bias (vs fixed (intrinsic) Fermi energy). Reprinted with permission from T. L. Barr, S. Seal, L. M. Chen, and C. C. Kao, Thin Solid Films 253, 277 (1994). Copyright (1994) with permission from Elsevier Science.

Non-thennal plasmas in contact with insulating walls (substrate) have an important property. The plasma with the hot electrons is positively charged relative to the wall (self-bias). A sheath with a positive space charge and an electric field is fonned between the wall and the plasma. The hot electrons travel faster to the wall than the heavy... 

Although the relationship between the channel charge and gate bias can be compHcated, it can be simply approximated as a capacitor stmcture. In this simplification the foUowiag equation holds, where q is the electron charge,... 

HBT Device Characteristics. The HBT consists of two back-to-back n—p diodes. In the most typical configuration the emitter—base diode is forward biased, with the coUector-base diode reverse biased. Because the current ia a forward-biased n—p diode is exponentiaUy dependent on the bias, smaU changes ia the emitter-base voltage result ia large changes ia the emitter current. The current across the emitter-base junction is a combination of the electrons iajected iato the base and the holes iajected iato the emitter. If the diode was semi-infinite to each side, the electron current density,/, could be expressed as foUows (44), where q is the electron charge, Vis the bias across the diode, kT... 

A light-emitting diode (LED) is a forward-biasedp—n junction in which the appHed bias enables the recombination of electrons and holes at the junction, resulting in the emission of photons. This type of light emission resulting from the injection of charged carriers is referred to as electroluminescence. A direct band gap semiconductor is optimal for efficient light emission and thus the majority of the compound semiconductors are potential candidates for efficient LEDs. 

Fig. 4.7. A semiconductor detector operated as a pin diode with a reverse voltage or bias. An incident X-ray photon ultimately produces a series of electron-hole pairs. They are "swept out" by the bias field of-500 V- electrons in the direction ofthe n-layer holes in the direction ofthe p-layer. Thus, a small charge pulse is produced after [4.21],...

The simplest polymer-based EL device consists of a single layer of semiconducting fluorescent polymer, c.g., PPV, sandwiched between two electrodes, one of which has to be transparent (Fig. 1-1). When a voltage or bias is applied to the material, charged carriers (electrons and holes) are injected into the emissive layer and these earners arc mobile under the influence of the high (> 105 V enr1) elec-... 

---