Effects of Dopants on the Complex Impedance and Dielectric Properties of Aluminum Nitride

Abstract

Complex impedance patterns of aluminum nitride (AIN) doped with various ions of different ionic sizes and valences have been examined at temperatures between 400" and 950°C. The patterns showed distinct differences between samples doped with ions of different sizes. Grain and grain boundary contributions to the resistance and capacitance were compared. It was found that the grain boundary: grain resistance ratio increases with density, Samples doped with large cations have higher effective dielectric constants at the grain boundary than samples doped with small cations or undoped samples, indicating a thinner grain-boundary layer.

Effects of carbothermal reduction on the thermal and electrical conductivities of aluminum nitride ceramics

“…The dielectric constant was calculated to be approximately 12, showing that the semicircle came from the AlN grains. Thus, the intercept of the semicircle must be related to ionic conduction of AlN grains similar to the previous study [12][13][14].…”

“…Jang and Choi [12,13] propose that the aluminum vacancies are the charge carrier for the AlN ceramics. Similar conclusions were also drawn from the DC polarization and impedance spectroscopy experiment, suggesting that ionic conduction of AlN grains was more dominant than electronic conduction, with grain boundary blocking effects [14].…”

“…The oxygen defects, substituting for a nitrogen ion and consequently produced aluminum vacancies, are believed to limit the electrical and thermal conductivity [11][12][13][14][15][16][17][18]. Jang and Choi [12,13] propose that the aluminum vacancies are the charge carrier for the AlN ceramics.…”

“…Oxygen impurity has been studied widely to understand the thermal and electrical properties of AlN ceramics [6][7][8][9][10][11][12][13][14][15][16][17][18]. An oxygen content of approximately 0.8 wt%, inherent to commercial AlN powder, is mostly removed from the AlN grains through forming a grain boundary second phase with sintering additives such as Y 2 O 3 and CaO [8][9][10].…”

Development of AlN ceramic composites for multilayer ceramic devices

“…To improve mechanical and electrical properties of AlN dielectric substrates large cations doping may be applied [14] ( Fig. 2).…”