Passivation and Generation of States at P-Implanted Thermally Grown and Deposited N-Type 4H-SiC/SiO2 Interfaces

In this work the effect of phosphorus on the electrical properties of n-type 4H-SiC MOS capacitors is studied. Phosphorus ions are implanted into the epitaxial layers prior to the deposition of SiO2 by PECVD, in shallow depths and at concentrations at the oxide-semiconductor interface in the range of (5 x 1017…1 x 1019) cm-3. Those samples are compared with 31P-implanted 4H-SiC MOS capacitors with thermally grown oxides, which were primarily investigated in the previous work of the authors. It is shown that independently of the oxide technology phosphorus may lead to decrease of the density of interface traps, whose response time to the AC voltage is longer than 1 µs. The side-effect of the implantation of phosphorus is generation of the very fast interface states, which are able to follow the frequencies over 1 MHz.

The Influence of Overaluminizing on TGO Formation on CMSX-4 Nickel Superalloy during Isothermal Oxidation

In the paper the formation of Thermally Grown Oxides on newly developed Thermal Barrier Coatings were described. The CMSX-4 Single Crystal nickel superalloy was used as a base material. The bondcoat was produced by overaluminizing of an MeCrAlY–type coating deposited by low pressure plasma spraying method (LPPS). The outer ceramic layer of yttria oxide stabilized zirconia oxide (Metco 6700) was deposited by plasma spray physical vapour deposition (PS-PVD). The isothermal oxidation test at 1100oC for 1000h shown that thickness of the TGO layer in overaluminized bondcoat was significantly thicker in comparison with conventional LPPS-sprayed MeCrAlY bondcoats in the same type of TBCs.