Effect of Crystal Orientation on Conductivity and Electron Mobility in Single‐Crystal Alumina

Abstract

The electrical conductivity of high-purity, single-crystal alumina is determined parallel to and perpendicular to the c-axis. The mean conductivity of four samples of each orientation is a factor 3.3 higher parallel to the c-axis than perpendicular to it. The conductivity as a function of temperature is attributed to extrinsic electron conduction at temperatures from 400" to 900°C and intrinsic semiconduction at temperatures from 900" to 1300°C. In the hightemperature regime, the slope on all eight specimens is 4.7 f 0.1 eV. Hence, the thermal bandgap at 0 K is 9.4 * 0.2 eV.

Highly textured TiN ceramic prepared by edge-free spark plasma sintering

“…The measured electrical resistivity perpendicular to the TS (3.40×10 −6 Ω·m) is higher than that perpendicular to the CS (1.93×10 −6 Ω·m). The main reasons for this phenomenon might be related to the more covalent bonds and ionic bonds on close-packed lll planes which restrict the free electrons transport process greatly [32]. Further study is needed to understand the mechanism of preferred orientation of textured TiN on the anisotropic electrical property.…”

Optical and electrical properties of silicon-implanted α-Al2O3

“…The current of the m-plane Al 2 O 3 sample was slightly higher than that of the c-plane Al 2 O 3 sample perhaps due to the anisotropy of electron effective mass. [37][38][39] The currents dramatically increased with decreasing contact spacing, indicating the high layer resistivities of silicon-implanted Al 2 O 3 . The temperature dependence of resistivity (ρ) at T m between 350 °C and 800 °C is shown in Fig.…”

“…We consider that T m below 800 °C is too small for the intrinsic carrier conduction of Al 2 O 3 , corresponding to the other reports. 16,38) In extrinsic carrier conduction, under the naturality condition in completely ionized donors, n is expressed as exp , 46) where N d is the donor concentration, N a is the acceptor concentration, 48) To determine μ, n, and carrier type, we attempted to conduct Hall-effect measurements with a direct current magnetic field of 0.6 T using the 10 × 10 and 100 × 100 μm 2 Van der Pauw patterns. Unfortunately, the reliable data were not obtained, probably due to the high resistivity of the Al 2 O 3 samples.…”