Dc bias

Figure 3-20 DC bias core selector chart (L= inductance with dc bias in millihenries /= dc current in amperes) (Courtesy of Magnetics, Inc.).

The etch rates were measured by a surface profiler and field emission scatming electron microscopy (FESEM), and the etch profile were observed by FESEM. In this study, a C /Ar gas chemistry was chosen to obtain high etch selectivity of Si film to niobium oxide mask since CI2 gas was known to be a good etch gas for Si films. The etch rate, etch selectivity and etch profile of niobium oxide nanopillars and Si films were explored by varying the CI2 concentration, coil RF power and dc bias voltage to substrate. 

The formation of Si nanodot arrays on a substrate was performed by ICPRIE of Si films using self-assembled niobium oxide pillars as an etching mask. The etch rates of niobium oxide pillars and Si films, and the etch selectivity of Si films to niobium oxide were investigated by varying etch parameters in a Ch/Ar gas. The main etch parameters used in this study were the concentration of CI2 gas, coil rf power, and dc-bias to substrate. 

Figure 1(a) shows the etch rates of niobium oxide pillar and Si film, and the etch selectivity of Si to niobium oxide as a function of CI2 concentration. The etch condition was fixed at coil rf power of 500 W, dc-bias to substrate to 300 V and gas pressure of 5 mTorr. As the CI2 concentration increased, the etch rate of niobium oxide pillar gradually decreased while Si etch rate increased. It indicates that the etch mechanism of niobium oxide in Cl2/Ar gas is mainly physical sputtering. As a result, the etch selectivity of Si film to niobium oxide monotonously increased. The effect of coil rf power on the etch rate and etch selectivity was examined as shown in Fig. 1(b). As the coil rf power increased, the etch rates of niobium oxide and Si increased but the etch rate of niobium oxide showed greater increase than that of Si. It is attributed to the increase of ion density with increasing coil rf power. Figure 1 (c)... 

Fig. 1. Etch rates of niobium oxide pillar and Si film, and etch selectivity of Si to niobium oxide piUar for the variation of (a) CI2 concentration, (b) coil rf power, and (c) dc-bias voltage to susceptor...

Fig. 2. FESEM images of (a) niobium oxide arrays before etching, and of Si nanodot arrays etched for (b) 20 s and (c) 30 s at 20% CI2, 500 W coil rf power, 300 V dc-bias voltage and 5 mTorr gas pressure...

Nonfaradaic components associated with the uncompensated resistance between reference electrodes (7 ) and the double layer capacitance (Qi) can be accurately determined by AC impedance measurements. In this technique, a small AC potential perturbation is superimposed to the DC bias, and the resulting AC current is measured as a function of the frequency of modulation. The simplest circuit considered for a polarizable... 

From the schematic representation in Fig. 18, it follows that for a perturbation featuring a DC bias light (Iq) and a sinusoidal component of amplitude /j,... 

Figure 6,9. Effective modulation of loser output as a function of radio frequency power applied to a Sharp LTQ24 laser diode at 30 MHz. Data are shown for DC bias of 50 mA ( , 7 mW laser output), 60 mA (O, 14 mW), and 70 mA (a, 19 mW). Reproduced from Ref. 25 with permission,...

One complication which may be present, when the Helmholtz model is in other respects appropriate, is that of specific adsorption. If one of the mobile species is to some extent chemically bound rather than being simply electrostatically bound to the metal electrode, Cji may show a dependence on the dc bias potential. Indeed this is the normal method of inferring specific adsorption. Another possibility in this case is that dl exhibits different high frequency and low frequency limits because at high frequencies the specific adsorption being an activated process is too slow to follow changes in interface potential. A further complication which is often present in real systems is the presence of an oxide layer on the surface of the metal electrode. Such an oxide layer can generate a potential... 

Flow rate. Substrate temperature, DC bias, RF power, RF reflection. 

Fig. 12 (a) Temperature dependence of the magnetoresistance for the junction shown in Fig. 10. The inset shows the corresponding junction resistance vs temperature with no applied magnetic field, (b) Magnetoresistance as a function of applied DC bias at 11 K for the same device in (a). Taken from [50] with permission...

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. 

Set up the DC Bias simulation (select PSpice and then New Simulation Profile) and then run PSpice (PSpice and then Run). When the simulation is complete, display the node voltage at Voc on the schematic ... 

In this section we will investigate how the DC current gain (Hfe) of a bipolar junction transistor varies with DC bias collector current Icq, DC bias collector-emitter voltage Vceq, and temperature. We will use the basic circuit shown below for all simulations ... 

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