Doping diffusion

BN bci3+nh3 1000-2000 B2H6+NH3 A00-700 High temp, ceramic Diffusion doping of Si... 

For micro PS a decrease in the specific resistivity by two or three orders of magnitude is observed if the dry material is exposed to humid air [Ma8] or vapors of polar solvents, e.g. methanol [Be6]. This sensitivity of PS to polar vapors can be used to design PS-based gas sensors, as discussed in Section 10.4. This change in resistivity with pore surface condition becomes dramatic if the pores are filled with an electrolyte. From the strong EL observed under low anodic as well as low cathodic bias in an electrolyte it can be concluded that micro PS shows a conductivity comparable to that of the bulk substrate under wet conditions [Ge8]. Diffusion doping has been found to reduce the PS resistivity by more than five orders of magnitude, without affecting the PL intensity [Ell]. 

Equation (10.1) can be used to determine the doping density of a silicon substrate and its depth profile, even if the flat band potential is not known accurately. Diffusion doping, ion implantation or the growth of an epitaxial layer are common methods of producing doped regions in semiconductor substrates. The dopant concentration close to the surface can be measured by SRP or capacitance-... 

Double-sided electrolytic contacts are favorable for this method of diffusion length measurement because they are transparent and the required SCRs are easily induced by application of a reverse bias. Therefore homogeneously doped wafers need no additional preparation, such as evaporation of metal contacts or diffusion doping, to produce a p-n junction. Furthermore, a record low value of surface recombination velocity has been measured for silicon surfaces in contact with an HF electrolyte at OCP [Yal], Note that this OCP value cannot be further decreased by a forward bias at the frontside, because any potential other than OCP has been found to increase the surface recombination velocity, as shown in Fig. 3.2. Note that contaminations in the HF electrolyte, such as Cu, may significantly increase the surface recombination velocity. This effect has been used to detect trace levels (20 ppt) of Cu in HF [Re5j. 

The wafers are processed into solar cells, the majority of which have a diode structure, as sketched in Figure 11.4, characterized by a thin, diffused, doped emitter, screen-printed front and back contacts and a front-surface antireflective coating. Prior to the effective cell manufacturing step, a chemical treatment of the silicon wafers removes... 

Modified by the addition, as applicable, of impurity diffusion (doping), ion implantation, epitaxy, etc. The active surface is processed into arrays of discrete devices or integrated circuits by metallization, passivation, or other means metallization of its back side (bottom surface) is optional. 

Modeling of the electrical characteristics of polymer LEDs is a challenging task, and at present there is no consensus as to the most appropriate model to apply. We note that the energy levels, mobilities, diffusivities, doping levels, and detailed structure of interfaces in polymer LEDs are poorly known at present. It is therefore difficult to distinguish between the effect of the bulk and the effect of the interfaces on the electrical behavior. It is also likely that many of the important parameters vary considerably between different polymers and even between the different samples of nominally the same polymer. 

The B doping by thermal diffusion associated with subsequent rapid thermal annealing (RTA) was employed for the fabrication of a MESFET by Tsai et al. (15). They made a very shallow channel of 50 nm by this method. This is the only successful result obtained with diffusion doping. 

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