Ideality factors

This relation differs from that given by Eq. 1 in so far as an ideality factor n is introduced in the exponential term. This factor may have different origins, which will not be discussed here. 

It was demonstrated that reproducible gas-sensitive silicon Schottky sensors could be produced after terminating the silicon surface with an oxide layer [71, 72]. This interfacial oxide layer permits the device to function as a sensor, but also as a diode, as the charge carriers can tunnel through the insulating layer. The layer made the Schottky diode behave like a tunneling diode, and the ideality factor could be voltage-dependent [73]. 

Figure 7.31 demonstrates the very good rectifying behavior of such a Pd Schottky diode on undoped ZnO thin film. The current density ratio determined for bias voltages of +0.6 V and -3V is about 104 as shown in the inset of Fig. 7.31. The ideality factor n is about 1.5. The temperature-dependent current-voltage (IV, see Fig. 7.31) and capacitance-voltage (CV) measurements from 210 to 300 K explain the reason for the slight deviation of the ideality factor from unity and the dependence of the reverse current on the reverse bias. The barrier heights of the diode of Fig. 7.31 jy and

Fig. 9.3. Electrical characteristics of a palladium/a-Si H Schottky barrier (a) the exponential forward current, the ideality factor, n, the reverse current, and the effects of annealing, described in Section 9.1.3 (6) the temperature dependence of the saturation current density plotted according to Eq. (9.14) (Thompson et at. 1981).

The contact leakage current for an ideal Schottky barrier is the saturation current J, which depends on the barrier height according to Eq. (9.14). Examples of the forward J-V characteristics of some p-4-n sensors are shown in Fig. 10.6 and compared with a palladium Schottky barrier sensor. The ideality factor of the p-i-n devices is... 

Sometimes an ideality factor of greater than 1 is also reported for a majority carrier device. In this case, however, there is no physical basis for an ideality factor of n > 1 and any deviation from n = 1 must have technological reasons. 

Electron density in the bulk and at the surface of a semiconductor Intrinsic electron density Ideality factor... 

Typical room temperature current-voltage (Z-V) characteristics of Ni/Au SDs are plotted in Figure 6.13. As we can see, the saturation current decreases monotonously with increasing SiN.r deposition time from 0 (the control sample) to 5 min which means that the effective Schottky barrier height increased owing to shallow defect reduction. Meanwhile, the series resistance and ideality factor also decreased when longer SiN deposition times were used. Based on the thermionic emission model, the forward current density at V > 3kT/q has the form [11] ... 

Using Equations (6.1) and (6.2), we calculated the barrier height and ideality factor which are listed in Table 6.2. For the sample without the... 

SiN nanonetwork, the barrier height is 0.76 eV. When the SiN deposition time is increased, the barrier height increases from 0.84 (3 min SiN ) to 1.13 eV (5 min SiN (). At the same time, the ideality factor reduces from 1.3 (no SiN ) to 1.06 (5 min SiN ) which indicates that the SDs are nearly ideal in samples grown with the SiN nanonetwork. Incidentally, this improved value is consistent with the work function of Ni (5.2 eV) and the electron affinity of GaN (4.1 eV). In the literature, a value of 1.099 eV (Ni) barrier height was achieved only after the GaN surface was treated with (NH S [12], which is known to passivate the surface defects albeit temporarily. Our results indicate that the Ni Schottky barrier height is very sensitive to the crystalline quality and the excess current... 

Alkaline CuCN solutions were used for the first time to electrodeposit homogeneous and adherent Cu films onto silicon. Tire obtained Cu/n-Si(lll) junctions show a nearly perfect rectifying behavior. The Schottky parameters (barrier height 3>b = 630 mV ideality factor n = 1.2) do not change importantly with time. It is also demonstrated that highly adherent Ni films can be plated onto n-Si(lll) from an acidic Watts bath, if copper clusters were elecrodeposited onto the silicon surface first. 

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