Effect of applied bias voltage on grain boundary potential barrier height (Φ b ) in semiconductor nanocrystals

2013 ◽  
Vol 9 (2) ◽  
pp. 227-230 ◽  
Author(s):  
T. Prakash ◽  
S. Ramasamy
Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3294
Author(s):  
Jakkree Boonlakhorn ◽  
Jedsada Manyam ◽  
Pornjuk Srepusharawoot ◽  
Sriprajak Krongsuk ◽  
Prasit Thongbai

The effects of charge compensation on dielectric and electrical properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics (x = 0−0.05) prepared by a solid-state reaction method were studied based on the configuration of defect dipoles. A single phase of CaCu3Ti4O12 was observed in all ceramics with a slight change in lattice parameters. The mean grain size of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics was slightly smaller than that of the undoped ceramic. The dielectric loss tangent can be reduced by a factor of 13 (tanδ ~0.017), while the dielectric permittivity was higher than 104 over a wide frequency range. Impedance spectroscopy showed that the significant decrease in tanδ was attributed to the highly increased resistance of the grain boundary by two orders of magnitude. The DFT calculation showed that the preferential sites of Al and Nb/Ta were closed together in the Ti sites, forming self-charge compensation, and resulting in the enhanced potential barrier height at the grain boundary. Therefore, the improved dielectric properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics associated with the enhanced electrical properties of grain boundaries. In addition, the non-Ohmic properties were also improved. Characterization of the grain boundaries under a DC bias showed the reduction of potential barrier height at the grain boundary. The overall results indicated that the origin of the colossal dielectric properties was caused by the internal barrier layer capacitor structure, in which the Schottky barriers at the grain boundaries were formed.


2004 ◽  
Vol 99 (1) ◽  
pp. 189-196 ◽  
Author(s):  
V. N. Vasyukov ◽  
A. D. Prokhorov ◽  
V. P. D’yakonov ◽  
H. Szymczak

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jinlong Jiang ◽  
Qiong Wang ◽  
Yubao Wang ◽  
Zhang Xia ◽  
Hua Yang ◽  
...  

The titanium- and silicon-codoped a-C:H films were prepared at different applied bias voltage by magnetron sputtering TiSi target in argon and methane mixture atmosphere. The influence of the applied bias voltage on the composition, surface morphology, structure, and mechanical properties of the films was investigated by XPS, AFM, Raman, FTIR spectroscopy, and nanoindenter. The tribological properties of the films were characterized on an UMT-2MT tribometer. The results demonstrated that the film became smoother and denser with increasing the applied bias voltage up to −200 V, whereas surface roughness increased due to the enhancement of ion bombardment as the applied bias voltage further increased. The sp3carbon fraction in the films monotonously decreased with increasing the applied bias voltage. The film exhibited moderate hardness and the superior tribological properties at the applied bias voltage of −100 V. The tribological behaviors are correlated to the H/E or H3/E2ratio of the films.


1990 ◽  
Vol 29 (Part 2, No. 11) ◽  
pp. L1977-L1980 ◽  
Author(s):  
Takeshi Takagi ◽  
Fumio Koyama ◽  
Kenichi Iga

2005 ◽  
Vol 20 (1) ◽  
pp. 62-67 ◽  
Author(s):  
E. György ◽  
A. Pérez del Pino ◽  
P. Serra ◽  
J.L. Morenza

Titanium targets with a bias voltage ranging from −500 to +500 V were submitted to multipulse high repetition rate Nd:yttrium aluminum garnet (YAG; λ = 1.064 μm, τ ∼ 300 ns, ν = 30 kHz) laser irradiations in nitrogen at intensity values below the single-pulse melting threshold. The morphology of the TiN structures formed under the cumulative action of the laser pulses on the surface of the unbiased and biased targets was investigated by profilometry and scanning electron microscopy. Under these irradiation conditions, a specific columnar surface microrelief developed. The height of the microcolumns reached about 10–15 μm, and their diameter about 1–2 μm. The development of TiN microcolumns was enhanced by the applied bias voltage. The enhancement in the negative biased samples was stronger than that in the positive biased ones.


2007 ◽  
Vol 76 (21) ◽  
Author(s):  
E. S. Cruz de Gracia ◽  
L. S. Dorneles ◽  
L. F. Schelp ◽  
S. R. Teixeira ◽  
M. N. Baibich

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