Dependence of acceptor levels and hole mobility on acceptor density and temperature in Al-doped p -type 4H-SiC epilayersIn order to obtain some of the parameters required to simulate the electric characteristics of silicon carbide (SiC) power electronic devices in a wide temperature range from startup temperatures ͑ഛ30°C͒ to steady-operation temperatures ͑ജ200°C͒, we discuss the dependence of the two donor levels on the total donor density ͑N D ͒ as well as the dependence of the electron mobility on the total impurity density ͑N imp ͒ and operating temperature ͑T͒ in the n-type 4H-SiC. The temperature-dependent electron concentration n͑T͒ and electron mobility n ͑T͒ in the n-type 4H-SiC epilayers with several nitrogen-doping densities are obtained from the Hall-effect measurements. By the graphical peak analysis method (free carrier concentration spectroscopy: FCCS) without any assumptions regarding the donor species, the two types of donor species are detected from n͑T͒. Moreover, the energy level and density of each donor species are determined by the FCCS. Using these results, we obtain the parameters with which the dependence of each donor level on N D can be simulated. Using n ͑T͒ at T Ͼ 250 K, moreover, we obtain the parameters with which the dependence of the electron mobility on N imp and T can be simulated.

In order to construct a reliable parameter set for the physical modeling of 4H-SiC, we are collecting and examining the physical parameters. The results of mobility measurement are presented and compared with the built-in model in the device simulator. The doping dependence of the electron mobility is in agreement with the built-in model, whereas that of the hole mobility is different from the built-in model in the higher doping region. Further, the anisotropy of the electron and hole mobility is investigated. The anisotropy of the electron mobility

Heavily carbon-doped GaAs was obtained by low-pressure metalorganic chemical vapor deposition by using trimethylgallium and arsine with a low V/III ratio. The hole concentration became as high as 2×1019 cm−3 without using intentional doping source gases when the V/III ratio was decreased to 2.4. The hole concentration coincided with the carbon concentration measured by secondary-ion mass spectroscopy. The epilayer surface tended to be rough when the V/III ratio was decreased below 10. However, when the V/III ratio was lowered to 2.4, the epilayer surface became completely mirror-like.

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Configurations of the basal plane dislocations in 4H-SiC epitaxial layers are classified into two types, having typical combinations of ‘straight Si-core and straight C-core’ and ‘straight Si-core and curved C-core’ partial dislocations. The core species are determined by the photoluminescence images and observation of the moving Si-core partial dislocations by ultra-violet light illumination. Each partial dislocation was analyzed by photoluminescence spectroscopy. As the results, C-core partial dislocations have been found to have different peak wavelengths depending on the excitation power of the illumination. Also from the detailed analysis of individual partial dislocations, the curved C-core partial dislocations have been found to have different characters which may be originated from the mixture of different types of dislocations. It has been suggested that this model is possibly described by continuous connection of 30o and 90o dislocations which have different configurations of dangling bonds. The difference in photoluminescence peak wavelength might be explained by the structural difference.