Sang-Hoon Chai

Misfit dislocation generated in InAs epilayer and InP substrate interfaces grown by metalorganic chemical-vapor deposition

Abstract The properties of InAs epilayer grown on (001) InP substrates (oriented 2° off (001) toward the [110] direction) using meta-organic chemical-vapor deposition (MOCVD) are reported. The epilayer of 17 nm thickness grown at 405 °C showed three kinds of misfit dislocation arrays. Their Burgers vectors in all cases were of the form a/2〈101〉 inclined 45° to the interface. Upon annealing 600, 140 and 220 nm InAs epilayers at 660 °C, most misfit dislocations became Lomer-type oriented exactly along the 〈110〉 direction. Average distance between misfit dislocations at early stage of growth was inversely proportional to the InAs thickness. This phenomena was interpreted to the relationship between the dislocation interaction energy and residual InAs epilayer strain energy.

Implementation of RF frequency synthesizer for smart utility network system

A wideband frequency synthesizer has been designed and fabricated to generate 780MHz(China), 868MHz(Europe), and 915MHz(Korea, North America) of three bands at the same time. It will be applied in the IEEE 802.15.4g SUN system. Measurement results show the frequency synthesizer has wide bandwidth of 1527~2020MHz(about 27.8% of center frequency) and low phase noise characteristics of -98.63dBc/Hz at 100KHz offset, -122.05dBc/Hz at 1MHz offset.

EC recycling technology for chemical reduction and energy saving in semiconductor or FPD fabrications

We have developed ethylene carbonate recycling process and system for chemical reduction and energy saving on photo-resist stripping and cleaning process, which will be a core process technology to get high performance and low price in semiconductor or FPD fabrications. Using this novel technology it is possible for the semiconductor wafer and FPD planer to process with low cost, and also there will be improvement of environmental pollution.