The orientation dependence of the piezoresistive effect of p-type single crystalline 3C-SiC thin film grown on a (100)Si wafer was characterized. The longitudinal, transverse gauge factors in [100] orientation, and longitudinal gauge factor in [110] orientation were found to be 5.8, −5.2, and 30.3, respectively. The fundamental piezoresistive coefficients π11, π12, and π44 of p-type 3C-SiC were obtained to be 1.5 × 10−11 Pa−1, −1.4 × 10−11 Pa−1, and 18.1 × 10−11 Pa−1, respectively. From these coefficients, the piezoresistive effect in any crystallographic orientation in p-type single crystalline 3C-SiC can be estimated, which is very valuable in designing micro-mechanical sensors.

Relaxation of interfacial stress and improved quality of heteroepitaxial 3C-SiC films on (100)Si deposited by organometallic chemical vapor deposition at 1200 °C

To lower deposition temperature and reduce thermal mismatch induced stress, heteroepitaxial growth of single-crystalline 3C-SiC on 150 mm Si wafers was investigated at 1000 o C using alternating supply epitaxy. The growth was performed in a hot-wall low-pressure chemical vapour deposition reactor, with silane and acetylene being employed as precursors. To avoid contamination of Si substrate, the reactor was filled in with oxygen to grow silicon dioxide, and then this thin oxide layer was etched away by silane, followed by a carbonization step performed at 750 o C before the temperature was ramped up to 1000 o C to start the growth of SiC. Microstructure analyses demonstrated that single-crystalline 3C-SiC is epitaxially grown on Si substrate and the film quality is improved as thickness increases. The growth rate varied from 0.44 to 0.76 ± 0.02 nm/cycle by adjusting the supply volume of SiH 4 and C 2 H 2. The thickness nonuniformity across wafer was controlled with ± 1 %. For a prime

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The influence of crystal defects on the gauge factor of p-type single crystalline 3C-SiC thin films is reported.

a b s t r a c tThe potential for enhancement of Si-based devices by growth of SiC films on large-diameter Si wafers is hampered by the very high temperatures (close to the Si melting temperature) that are needed for growth and doping by the existing techniques. Here, we present a unique doping method for growth of Al-doped single-crystalline 3C-SiC epilayers on 150 mm Si(1 0 0) substrates by atomic-layer epitaxy at 1000 1C using a conventional low-pressure chemical vapor deposition reactor. Al atomic concentration in the range of 2.8 Â 10 19 to 2.1 Â 10 20 cm À 3 , proportional to the supply volume of trimethylaluminium, is experimentally demonstrated. A doping mechanism, based on the supply sequence of precursors and reactor pressure, is proposed.

The advantages and disadvantages of using off-axis substrates for heteroepitaxial growth of 3C-SiC on Si(111) substrates are investigated in this paper. 3C-SiC is deposited on on-axis and 4° off-axis 150 mm Si(111) substrates using low pressure chemical vapour deposition. The dependence of surface morphology, roughness, crystallinity, alignment between the epilayer and the substrate, and film stress are evaluated using atomic force microscopy, x-ray diffraction, and wafer curvature measurement. Highly parallel steps are observed on both on-axis and off-axis Si substrates after surface preparation, yet step density is doubled and step height is much larger (> 21 times of single step height) for 4° off-cut Si compared to on-axis Si. X-ray diffraction results indicate that SiC grown on on-axis Si substrates are well-aligned with the Si substrates, while the SiC grown on off-axis substrates are tilted positively by as large angle as 1.66°. The well-aligned SiC grown on on-axis Si substrate exhibits lower and uniform residual stress compared to the film grown on off-axis Si substrates, which exhibits a nonuniform distribution of higher stress.The stress distribution is found to be dependent on Si surface step direction and height. These misorientation dependent tilting and stress distribution mechanisms are expected to be applicable to other hetero-epitaxial growth systems with similar mismatch magnitude.

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