| dc.description.abstract | Because the InP-based heterojunction bipolar transistor(HBT) has several merits of high electron mobility, high operation frequency, low turn-on voltage and combine with long wavelength fiber communication system, it’s the best choice for wire/wireless communication system, high speed digital circuit and fiber communication device applications.
This thesis used the InP/InAlGaAs materials to product heterojunction bipolar transistor for high-speed wireless communication system(Ka-band) and fiber communication system(40Gb/s). The transistor production include single heterojunction bipolar transistor(SHBT) and double heterojunction bipolar transistor(DHBT). In DHBT’s base-collector junction used InAlGaAs long grading and high doped layer to reduce the current blacking at DEC. We design different type of devices in mask lay-out, compare different type of devices and process with high-frequency characteristic and bring up the best type of device design.
In large size transistor devices, we demonstrated the current gain of InP/InAlGaAs SHBT(emitter size is 75 × 75 μm2) was 87 at collector voltage IC = 80 mA, the breakdown voltage(BVCEO) was 3V and the offset voltage(VCE,offset) was 150mV. Respectively, the current gain of InP/InAlGaAs DHBT(emitter size is 75 × 75 μm2) was 39 at collector voltage IC = 80 mA, the breakdown voltage(BVCEO) was 10V and the offset voltage(VCE,offset) was 90mV. DHBT can get improvement in breakdown voltage and offset voltage and suit to the power amplifier applications in high-speed wireless communication system.
We also demonstrated the small size transistor device(emitter size is 3 × 12 μm2, self-aligned technology) by ten mask process. The InP/InAlGaAs SHBT with cut-off frequency(ft) up to 80GHz and the maximum oscillation frequency(fmax) up to 58GHz, respectively, InP/InAlGaAs DHBT ft up to 78GHz and fmax up to 80GHz at collector voltage VCE = 2 V and collector current density JC = 50 kA/cm2. In the type of device design, the best device characteristic is fabricated by used self-aligned technology and the isolated pads type in the base and emitter ohmic contact metal. It’s effective to reduce the base-collector junction area and the base-collector junction capacitance and enhanced the high frequency characteristic of devices. | en_US |