Improvement of preferred orientation of NiAl/CrMn underlayers deposited on prebaked tape substrates
It was observed that the coercivity of CoCrPt films deposited on a polyimide tape was much lower than the coercivity deposited on a rigid glass substrate under identical conditions. X-ray diffraction showed that the desirable (112) and (110) texture of the NiAl/CrMn underlayers on the tape substrate was severely degraded during the deposition process. This resulted in the destruction of (10.0) growth texture of CoCrPt films and a significant reduction of magnetic coercivity. However, degassing of the tape substrate under vacuum before deposition significantly enhanced the magnetic properties. The coercivity of the film reached 170 kA/m which is near that achieved on a glass substrate. Auger analysis also revealed that oxygen was present in the NiAl/CrMn underlayers deposited without degassing the tape substrate.
Characterization of magnetic tapes and substrates
Ultra-thin advanced magnetic tape substrates are shown to have superior characteristics when compared to PET. In particular, PEN and ARAMID are viable alternatives to PET with elastic moduli that range from 4-5.4 GPa for PEN, and 10 GPa for ARAMID. Also, the ARAMID material is more isotropic than PET or PEN with a higher glass transition temperature of 277/spl deg/C. Thermal and hygroscopic expansion measurements show that PEN and ARAMID are typically superior to PET. Characteristics of two developmental materials (a polybenzoxazole and a polyimide) are also presented.
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.