Boron dopant

When the structure of a metal changes, it is because there is a driving force for the change. When iron goes from b.c.c. to f.c.c. as it is heated, or when a boron dopant diffuses into a silicon semiconductor, or when a powdered superalloy sinters together, it is because each process is pushed along by a driving force. 

The excellent insulating and dielectric properties of BN combined with the high thermal conductivity make this material suitable for a huge variety of applications in the electronic industry [142]. BN is used as substrate for semiconductor parts, as windows in microwave apparatus, as insulator layers for MISFET semiconductors, for optical and magneto-optical recording media, and for optical disc memories. BN is often used as a boron dopant source for semiconductors. Electrochemical applications include the use as a carrier material for catalysts in fuel cells, electrodes in molten salt fuel cells, seals in batteries, and BN coated membranes in electrolysis cells for manufacture of rare earth metals [143-145]. 

Fig. 5.16 shows the doping dependence of n obtained from sweep out, for the phosphorus, arsenic, and boron dopants, compared to the dangling bond density. The results confirm that n is about an order of magnitude less than the defect density and is even lower in the case of light boron doping. It should be noted that the value of actually depends quite sensitively on the thermal history of the sample, as is discussed in the next chapter, but it always remains less than the defect density. These data are for samples slowly cooled from the deposition temperature and stored at room temperature for an extended period and so are typical of samples that have not had any deliberate thermal treatment. 

Figure 4.15 Experimental and simulated boron dopant profiles, for two batch operating recipes [165].

Semiconductor technology shallow boron dopant on silicon... 

SRP. Spreading resistance profiling measures the response of the dopant atoms that reside at electrically active sites in the lattice. Combining NDP and SRP allows one to distinguish dopants, such as boron, that ire activated into electrically active sites from those located in nonactivated sites, such as in precipitates or interstitials. Therefore, the techniques can be used to select treatment methods that best activate the boron dopant and to provide information on the regions where non-electrically active dopant resides. 

If boron trichloride is used for the boron dopant together with a small excess of the carbon feedstock, sinterable SiC powders are obtained. 

It is crucial to dope the diamond with enough boron to impart sufficient electrical conductivity on the matrix that the material can be considered metal-like. It is thus essential to consider how the boron dopant density, denoted in B atoms per cubic centimeter, affects the electrical resistivity of the material [14], as shown in Figure 5.1a. Note that diamond contains 2 x 10 C atoms per cubic centimeter. Boron doping introduces a band acceptor level 0.37 eV above the valence band. In the boron dopant range 10 -10 B atoms per cubic centimeter (i.e., 1 in 2 X10 - 1 in 2 X 10 C atoms are replaced with B), the material shows resistivity changes in accordance with p-type semiconductor behavior. The implications... 

For both redox species, as the boron concentration increases A p decreases until a value close to that synonymous with metal-like behavior is reached at boron concentrations >10 B atoms cm . Note the change in A p is much more dramatic with Ru(NH3)g and is evident for all boron dopant densities less... 

Acharya CK, Turner CH (2006) Stabilization of platinum clusters by substitutional boron dopants in carbon supports. J Phys Chem B 110(36) 17706-17710... 

The accumulation of boron dopant is likely to result in the formation of conductive disks. Moreover, the conductive sites, which are smaller than the tip, must be biased to exert a positive feedback effect, indicating that these sites are connected to the underlying p-type silicon wafer through conductive pathways across a 1-10 pm thick diamond film. It was suggested that such sites are formed at the grain boundaries of polycrystalline BDD. In addition, the recent SECM study of microcrystalline and nanocrystalline BDD films revealed that the locations of highly electroactive regions depend on redox mediators [51], Mediator-dependent local electroactivity was also observed by SECM for BDD under unbiased conditions [52] and for the films and particles of undoped nanodiamonds at various potentials [53]. 

Boron plays a dual role, both as a dopant and as a flux for the preparation of LiNi02- The heat-treatment temperature and the time decrease with increasing boron content. Boron dopant may displace Ni + to 3a sites, leading to an increased Ni content in the boron-doped nickel oxides, thus enhancing the electrochemical activity. In addition, because the bond energy of B-O (809 kj/mol) is larger than those of Ni-O (380 kj/mol) and Li-O (78 kj/mol), the stability of the structure of the doped LiNii j.Bj.O2 compounds is increased. 

Thus, the known sectorial character of the HTHP diamond crystals [ 27 ] well manifests itself in the electrochemical measurements. On the whole, the difference in the electrochemical behavior of the individual faces can he primarily ascribed to different boron concentration in their adjacent growth sectors, resulting from the different ability of the diamond crystal faces to incorporate the boron dopant during the growth process, rather than to different surface atomic densities or other purely surface properties. 

---