Fig. 1. Epi-layer structure and energy band diagram of device. (a) Epi-layer structure; (b) simulated energy band diagram

Fig. 2. Microscope image and cross section schematic diagram of flip-chip bonded photodetector. (a) Microscope image; (b) schematic diagram of cross section

Fig. 3. Comparison diagrams of dark current, equivalent circuit, and physical parameters of device. (a) Relationship curves between dark current and reverse bias voltage of device with active region diameter of 4 μm; (b) equivalent circuit diagram of balanced photodetector; (c) comparison between device capacitance value extracted from S11-parameter and simulated junction capacitance value; (d) comparison between device resistance value extracted from S11-parameter and simulated resistance value

Fig. 4. Principle diagram of frequency response measurement system

Fig. 5. Frequency response of devices. (a) Device with active region diameter of 4 μm; (b) device with active region diameter of 6 μm; (c) device with active region diameter of 8 μm; (d) comparison between simulated bandwidth and measured bandwidth

Fig. 6. RF output power and photocurrent of devices. (a) Device with active region diameter of 8 μm at 47 GHz; (b) device with active region diameter of 8 μm at 47 GHz

Fig. 7. Summary of the RF output power achieved by advanced balanced photodetectors at different frequencies in recent years