Search

The heteroepitaxial growth of TiN on MgO(001), deposited by reactive magnetron sputtering, has been studied in situ. Using real-time specular x-ray reflectivity, layer-by-layer growth was observed, with the surface roughening decreasing with an increase in the deposition temperature. Higher temperatures also resulted in lower growth rates. The film thickness was measured with specular x-ray reflectivity. Using off-plane Bragg–Brentano as well as grazing incidence in-plane wide angle scattering, the pseudomorphic growth of TiN to the underlying MgO(001) was established. Transmission electron microscopy reveals atomic planes passing through the MgO–TiN boundary, thus confirming heteroepitaxial growth. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The formation of crystalline SiC by implantation of C ions into silicon is not a single-step process. The implantation results in an elastic distortion of the Si matrix lattice and in the formation of crystalline SiC particles, depending on ion fluence and thermal conditions during implantation and postannealing. The growth of the SiC particles in the Si matrix was studied with various synchrotron x-ray scattering techniques and high-resolution transmission electron microscopy. Crystallites of the 3C–SiC polytype are formed in a buried layer. Three groups of crystallites with different orientation relative to the Si matrix are found: with a random orientation like in a powder material, with a fiber texture axis parallel to the surface normal, and completely aligned to the Si matrix lattice due to a partially coherent growth of SiC in the Si matrix. The thermal treatment favors the growth of highly oriented material: a higher implantation temperature is more efficient than a postimplantation treatment even at higher temperatures.© 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Boron was implanted with four energies and doses at 400 °C into 6H-SiC epilayers to form a 500 nm thick doped layer with a mean concentration between 1x10[sup 18] and 1.5x10[sup 21] cm[sup -3]. Two annealing techniques were used: furnace and flash lamp annealing. The electrical and microstructural effects were investigated using temperature dependent Hall measurements, cross sectional electron microscopy, and secondary ion mass spectrometry. During the annealing two competing processes occurred: boron outdiffusion and growth of boron containing precipitates. The efficiency of these individual processes is different for varying dopant concentrations as well as annealing techniques. After furnace annealing at temperatures between 1550 and 1750 °C and for a mean boron concentration of 5x10[sup 19] cm[sup -3] boron containing clusters are found mainly around the region of the three deeper implantation peaks. In the surface region boron outdiffusion is observed adjusting a concentration of 1.5x10[sup 19] cm[sup -3]. Using flash lamp annealing, the outdiffusion is negligible. For high dopant concentrations (1.5x10[sup 21] cm[sup -3]) the growth of random distributed boron precipitates is the dominating effect independent of the used annealing techniques. The electrical activation is limited due to the solubility of boron in SiC. After furnace annealing Hall effect measurements show a maximum hole concentration of about 2x10[sup 16] cm[sup -3] for the boron concentration of about 5x10[sup 18] cm[sup -3]. Alternative to the furnace annealing, the electrical properties after flash lamp annealing at about 2000 °C, 20 ms show a slight enhancement of the maximum hole concentration for boron concentrations <3x10[sup 20] cm[sup -3]. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Strong gettering of Cu atoms beyond the projected ion range R[sub P] has been found in single-crystal Si implanted with P[sup +] and As[sup +] ions at MeV energies. We call this phenomenon the "trans-R[sub P] effect." The formation of a separate Cu gettering band below R[sub P], as detected by secondary ion mass spectrometry, indicates the presence of a significant amount of defects therein. These defects have not been detected by transmission electron microscopy and we suggest that they are small interstitial clusters. The amount of Cu atoms gettered beyond R[sub P] is, particularly for the P implants, much greater than that in the gettering layer at R[sub P], indicating that the gettering ability of the point defects beyond R[sub P] is higher than that of the extended defects at R[sub P]. A mechanism responsible for their formation and clustering in the trans-R[sub P] region is proposed, and an explanation is given of the differences in the results for the P and As implants. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Low-resistivity (<0.1 Ωcm), p-type SiC layers of about 500 nm width and targeted acceptor concentrations of 1.5×10[sup 20] cm[sup -3] and 5.0×10[sup 20] cm[sup -3] were produced by the combination of high-dose (1.0 and 3.3×10[sup 16] cm[sup -2]), multienergy (50-450 keV) Al[sup +] ion implantation of 6H-SiC at -130°C, ion-beam-induced crystallization with 500 keV, 5×10[sup 15] Si[sup +] cm[sup -2] at 500°C and subsequent furnace annealing at 1500°C for 10 min. The implanted SiC layers have a nanocrystalline structure consisting of randomly oriented grains of mainly 3C-SiC. The electrical properties of the doped, nanocrystalline layers were investigated by sheet resistance and Hall measurements in dependence on temperature and compared with results from single-crystalline reference samples. In comparison with the standard doping process, the hole concentration at 50 °C is enhanced by more than one order of magnitude from 9.0×10[sup 17] cm[sup -3] to 1.6×10[sup 19] cm[sup -3] in the case of 1.5×10[sup 20] Al cm[sup -3] and from 6.1×10[sup 18] cm[sup -3] to 8.0×10[sup 19] cm[sup -3] in the case of 5.0 ×10[sup 20] Al cm[sup -3], respectively. It can be speculated that the loss of active Al acceptors by precipitation is reduced in the nanocrystalline layers and, therefore, the critical concentration for the formation of an impurity band can be achieved. [ABSTRACT FROM AUTHOR]

Five different species, namely B, Si, P, Ge, and As, were implanted at MeV energies into (100)-oriented n-type Czohralski Si, in order to form deep gettering layers during the subsequent annealing. Then the samples were contaminated with Cu by implanting the impurity on the backface and performing additional annealing. The resulting Cu depth distributions were measured by secondary ion mass spectrometry. Strong gettering of Cu atoms beyond the projected ion range R[sub P] and formation of a well-defined separate Cu gettering band therein is found for P and As implants. We call this phenomenon the "trans-R[sub P] effect." It arises from the presence of a significant amount of defects in the regions much deeper than R[sub P]. Their gettering ability is higher than that of the extended defects around R[sub P], as the amount of Cu atoms gettered beyond R[sub P] is, especially for the P implants, much greater than that in the implanted gettering layer at R[sub P]. These deep defects have not been detected by transmission electron microscopy, and we suggest that they are small interstitial clusters. A mechanism responsible for the migration of self-interstitials from R[sub P] into the trans-R[sub P] region and their clustering therein is proposed. An explanation is given of the possible reasons for the differences in the results for the P[sup +] and As[sup +] implants. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]