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Nano-ridge engineering (NRE) is a novel heteroepitaxial approach for the monolithic integration of lattice-mismatched III-V devices on Si substrates. It has been successfully applied to GaAs for the realization of nano-ridge (NR) laser diodes and heterojunction bipolar transistors on 300 mm Si wafers. In this report we extend NRE to GaSb for the integration of narrow bandgap heterostructures on Si. GaSb is deposited by selective area growth in narrow oxide trenches fabricated on 300 mm Si substrates to reduce the defect density by aspect ratio trapping. The GaSb growth is continued and the NR shape on top of the oxide pattern is manipulated via NRE to achieve a broad (001) NR surface. The impact of different seed layers (GaAs and InAs) on the threading dislocation and planar defect densities in the GaSb NRs is investigated as a function of trench width by using transmission electron microscopy (TEM) as well as electron channeling contrast imaging (ECCI), which provides significantly better defect statistics in comparison to TEM only. An InAs/GaSb multi-layer heterostructure is added on top of an optimized NR structure. The high crystal quality and low defect density emphasize the potential of this monolithic integration approach for infrared optoelectronic devices on 300 mm Si substrates.

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This paper describes the results of experimental evaluation of titanium dioxide thin films formed by CVD as active layers in semiconductor, resistive sensors for detection of ethanol vapors. TiO 2 layers with a thickness of 90 nm are formed by CVD in the TTIP-O 2 -O 3 -Ar reaction system. Sensors manufactured with titania films formed under all the deposition conditions studied exhibit good electrical response to the ethanol vapors, with quick response-recovery characteristics in the temperature range 170-300 8C. Sensor performance is determined by the relative amount of anatase phase and grain size in the films. The response value (R air /R ethanol ) of the sample with the highest degree of crystallinity reached 37 at an operating temperature of 200 8C.

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