HIGH POWER PERFORMANCE USING InAlAsDnGaAs SINGLE HETERO JUNCTION BIPOLAR TRANSISTORS

The power performance of InP based single HBTs has been mediocre compared with their double HBTs counterparts due to their inherently low breakdown voltage. [ 11 For power amplifiers requiring moderate output power levels, single HBTs are more cost effective due to their simplicity of fabrication and design. InP-based single HBTs have demonstrated power performance at lOGHz of 1.37mW/pm2, lldB gain and 33.9 % power-added-efficiency [2]. In this work, a graded InAlAshGaAs emitter base junction and a lowdoped thick collector was employed to lower the turn-on voltage and increase the breakdown voltage respectively. InAlAdInGaAs single HBTs were subsequently fabricated with undercut collectors for reduced base-collector capacitance. A 4-finger 2x10 pm2 HBT unit cell exhibited 22.5 dBm continuous wave (CW) output power (2.23mW/pm2 power density), 35 % power-added-efficiency and an associated gain of 10.5dB at 1OGHz. To our knowledge, this is the best output power density performance for InP based single HBTs. I