Electrical properties of boron delta-layers in silicon

726-731<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Electrical properties or MBE grown boron δ- layer in Si have been investigated in the temperature range 10-300 K and a comparative study with their uniform doping counterpart has been presented. Various boron doping levels from 1012-1014 <span style="font-size:14.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">cm-2 in the δ- layer show that, with the fall of temperature from 300 to 50 K. Hall mobility first increases followed by a rapid decrease, and at temperature ≤50 K, it becomes almost constant. Higher doping level in the sample grossly lowers the value of Hall mobility but its variations with temperature are almost similar to each other. Existence of the dominant carrier scattering mechanism has also been reported. In all the samples, freeze-out of carriers have been clearly noticed below 100K. Existence of a Mott metal-non-metal transition in the sample has been observed at low temperature region when the doping <span style="font-size:14.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">concentration exceeds a critical high value of 6×10-13 cm-2, and this has been found consistently with the other observations like zero activation energy and negative TCR. The value of minimal metallic conductance for the samples has also been reported.</span

<span style="font-size: 22.5pt;mso-bidi-font-size:15.5pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">Anomalous resistive transition and frequency dependent dielectric constant of <span style="font-size:21.5pt; mso-bidi-font-size:14.5pt;font-family:"Arial","sans-serif";mso-bidi-font-weight: bold;mso-bidi-font-style:italic">Zn_1-_{<span style="font-size:23.0pt;mso-bidi-font-size:16.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold;mso-bidi-font-style:italic">x</span>}<span style="font-size:23.0pt;mso-bidi-font-size:16.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold;mso-bidi-font-style:italic">M_xO <span style="font-size:22.5pt;mso-bidi-font-size:15.5pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">[M=Li (Mg, Ba)] system </span></span></span></span>

211-216<span style="font-size: 15.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">The II-VI materials of Zn1-xMxO have been synthesized by solid-state reaction method and their structural, electrical and dielectric properties studied. The lattice parameters of these materials are found to be consistent with the reported values. The dielectric constant measured at different five frequencies agrees well with the published values and found to be maximum for doping concentration <span style="font-size:15.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">x= 0.2, at all frequencies. A de resistive anomaly was found for all samples at a certain temperature called transition temperature (Td-s) from dielectric to semiconducting state, which depends on the concentration and nature of the dopant atoms in ZnO. </span

Ultrahigh Thermoelectric Performance of ZnO-CdO Thin Films

Zinc oxide (ZnO) is emerging as a promising n-type thermoelectric material (TE) for power harvesting due to its high melting point and large Seebeck coefficient. However, the TE performance of ZnO is limited by high thermal conductivity and low carrier mobility. Adding or doping a divalent element such as cadmium oxide (CdO) can lower the thermal conductivity and enhance the carrier concentration of ZnO. In this paper, the thermoelectric transport properties of ZnO-CdO nanocrystalline thin films are investigated by varying the Zn/Cd ratio at temperatures ranging from room temperature (RT) to 423 K. The electrical conductivity, carrier concentration and mobility of ZnO were enhanced by increasing the Cd concentration. The maximum power factor of 2.75 × 10−4 W m−1 K−2 was obtained at 423 K for the Zn/Cd = 1:3 sample. The thermal conductivity was dominated by lattice thermal conductivity in which Umklapp scattering occurs between anharmonic phonons. The thermal conductivity of ZnO decreased significantly with increasing Cd concentration. The highest estimated figure of merit (ZT) of 0.59 was found at 413 K for the Zn/Cd = 1:3 sample, which is 223 times greater than for ZnO, indicating that the film is efficient in energy generation