Doping semiconducting material

Concept Check 18.4 At relatively high temperatures, both donor- and acceptor-doped semiconducting materials exhibit intrinsic behavior (Section 18.12). On the basis of discussions of Section 18.5 and this section, make a schematic plot of Fermi energy versus temperature for an n-type semiconductor up to a temperature at which it becomes intrinsic. Also note on this plot energy positions corresponding to the top of the valence band and the bottom of the conduction band. 

Plenary 14. A K Ramdas et al, e-mail address akr phYsics.purdue.edu (RS). Electronic RS studies of doped diamond as potential semiconducting materials. A Raman active Is (p3 2) ls (Pi/2 transition of a hole... 

Selective doping alters a single semiconducting material to form within it a p-n junction. Single-crystal or multi-crystalline silicon are the most common examples of this type of cell, with other examples including GaAs and InP, see Table 8.2. In order to improve conversion efficiency various design aspects can he considered and varied such as material purity and crystallinity, depth of the p/n junction helow the materials surface, and amount and distrihution of dopant atoms on either side of the p/n junction. 

A general feature of doped semiconductive NC materials is described in a review paper authored by Bhargava, one of the founders of this area (8). It is generally accepted that solid particles are richer in crystallographical defects when their diameter becomes smaller. Quantum size effects associated with nanoparticles are very sensitive to the defects. In most cases, defects influence negatively the luminescent properties of phosphors. Most of these drawbacks of NC phosphors are attributed to the larger specific surface area, since defects tend to concentrate themselves in a near-surface region. 

From the electronic perspective, poly(a-thiophene) is an excellent semiconducting material when doped. While poly(a-thiophene) itself is intractable and therefore not processable, the poly(3-alkyl-a-thiophene)s are soluble and still exhibit conductivities comparable to the unsubstituted derivatives. 

Semiconducting c-BN was synthesized by Wentorf [286] using HP-HT methods. For p-material Be doping was used, the n-type was produced by doping the material with S, Si, or KCN. 

Layers Typical materials for which CMP processes originally have been developed for microelectronic applications include various types of silicon dioxide such as thermal oxide, TEOS, HDP, BPSG, and other B- or P-doped oxide films. These films are used for various isolation purposes including interlevel dielectric (ILD), intermetal dielectric (IMD), or shallow trench isolation (STI). In addition, n- or p-doped poly-Si, which is a semiconducting material used as capacitor electrode material for DRAMS or gate electrode for MOS applications (CMOS as well as power MOS devices), also has to be polished. Metals for which CMP processes have emerged over the last 10-15 years are W for vertical interconnects (vias) and most importantly Cu as a low-resistivity replacement for aluminum interconnects, employed in the damascene or dual-damascene processing scheme. Other metals that are required for future nonvolatile memories are noble metals like Pt or Ir for which CMP processes have been explored. 

These detectors are made of semiconducting materials. In these detectors, solid-state electrodes are made from Li doped with Si or Ge. The resolution is approximately 1-2 keV for 1 MeV y-Rays and sometimes provides a greater than 10-fold improvement over Nal (Tl) scintillation detectors, described below. These are commercially available and more often used in research-grade instruments. 

A certain relationship, which exists between the bulk and surface properties of semiconducting materials and their electrochemical behavior, enables, in principle, electrochemical measurements to be used to characterize these materials. Since 1960, when Dewald was the first to determine the donor concentration in a zinc oxide electrode using Mott-Schottky plots, differential capacity measurements have frequently been used for this purpose in several materials. If possible sources of errors that were discussed in Section III.3 are taken into account correctly, the capacity method enables one to determine the distribution of the doping impurity concentration over the surface" and, in combination with the layer-by-layer etching method, also into the specimen depth. The impurity concentration profile can be constructed by this method. It has recently been developed in greatest detail as applied to gallium arsenide crystals and multilayer structures. 

Chemical substitution has been used as a probe of the origin of the high transition temperature in YBa2Cu30y. The properties of this material are best understood when the material is considered to be a semiconductor doped to metallicity. When oxygen doped, the material becomes a 1 dimensional excitonic superconductor. The intrinsic semiconducting energy gap then provides the mechanism for the extremely... 

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