Tsung-Hsin Lee

Schottky mechanism for Ni∕Au contact with chlorine-treated n-type GaN layer

To investigate the function of chlorination treatment, Schottky diodes with Ni∕Au contact and chlorine-treated n-type GaN were fabricated. The resultant Schottky barrier height and ideality factor of the chlorine-treated Schottky diodes were improved. The corresponding increase in photoluminescence intensity and carrier lifetime of the chlorine-treated n-type GaN was achieved using photoluminescence and time-resolved photoluminescence measurements. The improved performance of chlorine-treated Schottky diodes was attributed to the reduction of surface states as a result of reduced Ga dangling bonds and the N vacancies being passivated by the formation of GaOx on the surface of n-type GaN.

Electromagnetic Source Azimuth Measurement Using Electrooptical Electromagnetic Field Probe

A new type electrooptical electromagnetic field probe was fabricated by combining three magnetic field sensors, each of which consists of a Mach-Zehnder modulator and an integrated annular antenna. The frequency response was flat from 50 MHz to 2.2 GHz. The average minimum detectable electromagnetic field intensity of the sensor is 2.22 mV/m. When the probe axis was pointed toward the electromagnetic radiation source, the highest sensitivity was obtained. The variation of the sensitivity is within plusmn0.5 dB with rotating the probe around its axis. This result indicates that the azimuth of the electromagnetic radiation source can be measured.

Integrated LiNbO3 Mach-Zehnder type electrooptical electromagnetic sensor

An integrated electromagnetic field sensor using Z-cut LiNbO3 Mach-Zehnder waveguide modulator and micro antenna was fabricated and measured. A coplanar waveguide antenna was directly integrated with the traveling-wave electrode of the Mach-Zehnder waveguide modulator on the same LiNbO3 substrate. The minimum detectable electric field strength is 8.91 times 10-4 V/m at 2 GHz.

Arrayed-waveguide grating multiplexer with graded-index free propagation region

Arrayed-waveguide multiplexer which is used a novel graded-index free propagation region is obtained flat and broadened spectral response. The 1 dB and 3 dB wavelength pass band will increase while increasing the graded-index FPR length.