High density p-type Bi0.5Sb1.5Te3 nanowires by electrochemical templating through ion-track lithography

We have investigated the preparation of crystalline germanium films by the solid phase crystallization (SPC) of amorphous germanium (a-Ge) precursor on single crystalline silicon substrates. The a-Ge precursor easily incorporates the impurities from the surface exposed to the air, and the impurities affect the crystallinity after the SPC. In the a-Ge precursor prepared by Knudsen-cell evaporation, the preferential crystalline growth following the Si substrates is disturbed by the high density of impurities and the random crystalline structures are formed. The a-Ge precursors prepared by electron beam evaporation have high impurity concentrations only near the surface because the impurity diffusion is slow because of the relatively high density. The preferential growth is successfully obtained in a-Ge precursor prepared on n-type Si substrates, although the random crystallization is slightly observed on p-type Si substrates. By sufficiently reducing the impurity concentrations by avoiding the air exposure, the preferential growth can be promoted on p-type Si substrates. The impurity incorporation because of the air exposure is sufficiently reduced for the preferential growth by covering a-Ge with a-Si blocking layers. This method is effective for future practical applications of SPC Ge films.

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Realization of high mobility p-type co-doped ZnO: AlN film with a high density of nitrogen-radicals

Thin Solid Films ◽

10.1016/j.tsf.2009.01.171 ◽

2009 ◽

Vol 517 (14) ◽

pp. 3950-3953 ◽

Cited By ~ 6

Author(s):

Jong Hyun Lee ◽

Jun Seok Lee ◽

Seung Nam Cha ◽

Jong Min Kim ◽

Do Seok Seo ◽

...

Keyword(s):

High Mobility ◽

High Density ◽

Aln Film ◽

Nitrogen Radicals ◽

Doped Zno ◽

P Type ◽

Co Doped

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High Density Low Leakage SRAM Standby Current Reduction with a Channel Stop Implant in p-Type Well in 40nm CMOS Development

ECS Transactions ◽

10.1149/05201.0111ecst ◽

2013 ◽

Vol 52 (1) ◽

pp. 111-116

Author(s):

Y. Li ◽

J. Tao ◽

S. K. Huang ◽

D. Lin ◽

S. Zhang ◽

...

Keyword(s):

High Density ◽

Low Leakage ◽

Current Reduction ◽

P Type

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Enhanced Thermoelectric Figure-of-merit at Room Temperature in Bulk Bi(Sb)Te(Se) With Grain Size of ∼100nm

MRS Proceedings ◽

10.1557/opl.2013.948 ◽

2013 ◽

Vol 1543 ◽

pp. 93-98 ◽

Cited By ~ 1

Author(s):

Tsung-ta E. Chan ◽

Rama Venkatasubramanian ◽

James M. LeBeau ◽

Peter Thomas ◽

Judy Stuart ◽

...

Keyword(s):

Grain Size ◽

Mechanical Alloying ◽

Grain Boundaries ◽

Figure Of Merit ◽

Room Temperature ◽

High Energy ◽

High Density ◽

Nanocrystalline Powders ◽

Bulk Materials ◽

P Type

ABSTRACTGrain boundaries are known to be able to impede phonon transport in the material. In the thermoelectric application, this phenomenon could help improve the figure-of-merit (ZT) and enhance the thermal to electrical conversion. Bi2Te3 based alloys are renowned for their high ZT around room temperature but still need improvements, in both n- and p-type materials, for the resulting power generation devices to be more competitive. To implement high density of grain boundaries into the bulk materials, a bottom-up approach is employed in this work: consolidations of nanocrystalline powders into bulk disks. Nanocrystalline powders are developed by high energy cryogenic mechanical alloying that produces Bi(Sb)Te(Se) alloy powders with grain size in the range of 7 to 14 nm, which is about 25% finer compared to room temperature mechanical alloying. High density of grain boundaries are preserved from the powders to the bulk materials through optimized high pressure hot pressing. The consolidated bulk materials have been characterized by X-ray diffraction and transmission electron microscope for their composition and microstructure. They mainly consist of grains in the scale of 100 nm with some distributions of finer grains in both types of materials. Preliminary transport property measurements show that the thermal conductivity is significantly reduced at and around room temperature: about 0.65 W/m-K for the n-type BiTe(Se) and 0.85 W/m-K for the p-type Bi(Sb)Te, which are attributed to increased phonon scattering provided by the nanostructure and therefore enhanced ZT about 1.35 for the n-type and 1.21 for the p-type are observed. Detailed transport properties, such as the electrical resistivity, Seebeck coefficient and power factor as well as the resulting ZT as a function of temperature will be described.

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OBIC Measurements on 6H-SiC Schottky Diodes

MRS Proceedings ◽

10.1557/proc-423-51 ◽

1996 ◽

Vol 423 ◽

Cited By ~ 4

Author(s):

K. Rottner ◽

A. Schöner ◽

M. Frischholz ◽

R. Helbig

Keyword(s):

Surface Charge ◽

Electric Field Distribution ◽

Schottky Diodes ◽

Surface States ◽

Depletion Region ◽

Schottky Contacts ◽

High Density ◽

Negative Surface ◽

Negative Surface Charge ◽

P Type

AbstractThe OBIC (Optical Beam Induced Current) technique is a powerful method to investigate the electric field distribution of p-n junctions in SiC. In a previous work we found strong indications for the presence of a high density of negative surface charge in n-type SiC. In order to study samples of both conductivity types under similar conditions we prepared Schottky contacts on ntype and p-type 6H-SiC CVD epitaxial layers.OBIC measurements show an extension of the depletion region of several hundreds of microns from the edge of the contact on n- and p-type samples, thus interconnecting diodes on an area up to several mm2. Our results imply that there is no fixed surface charge but a high density of both acceptor- and donorlike surface states leading to a dependence of the net surface charge on the Fermi energy, in which case the sign of the surface charge reverses from negative on ntype material to positive on p-type 6H-SiC.

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