We explain our device study from design, fabrication to measurement with equipments
Device design and mask pattern fabrication
First is the design of optical device. Optical waveguide mask pattern is fabricated by using BPM cad or Fortran program.
Crystal growth
The performance of optical device is almost determined by the growth of waveguide wafer.
Metal organic vapour phase epitaxy system is used for the crystal growth.
In, Ga, Al, As, P compound semiconductor material growth is possible.
Precursors are TMI, TEG, TMA, TBA, TBP, and p-, n- type dopant are DEZ and DTBSi.
Ozon cleaner is used for the wafer cleaning before growth, and Helium leak detector is used for leakage check of the system.
SiO2 CVD
SiO2 film is necessary in the semiconductor process as a etching mask or insulator as a elctrode isolation.
We have introduced the Plasma CVD using TEOS.
Lithography
Optical waveguide is patterned on the wafer by photo lithography system (MJB4) using glass mask.
Etching
Optical waveguide is fabricated using wet chemical etching or dry etching by using the photo lithographied pattern.
Electrode fabriation
Original wafer is thinned by the lapping system for the ease of cutting of device.
Electrode is evaporated by the evaporator with resistance heating or electron beam evaporator.
Evaporated metal is annealed to reduce the electrical resitance between metal and semiconductor.
Dye bonder or wire bonder is used for the package.
Structure measurement
Quantum dots structure are measured by atomic force microscope.
Waveguide thickness or the step height is measured by laser microscope.
Photoluminescence
Absorption edge of the wafer is measured by Photoluminescence measurement.
Electrical measurement
Current voltage characteristics is measured by source measure unit. Electrical
characteristics such as MOSFET is measured using prover. Current voltage
or current light characteristics are measured by pulse I-L tester.
Near field pattern measurement
Near field pattern, that is the output light intensity from the device is measured by NFP measurement system.
Tunable laser is used as input light, and the ouput light pattern is observed by visicon camera and optical power is measured by power meter.