Partially Gaussian doping profile in the collector layer optimizes the electric field intensity and distribution, enabling a broader range of photo-generated electrons to attain peak drift velocities. This specific doping strategy effectively suppresses space-charge effects and field collapse even under high optical intensities, thereby significantly enhancing the bandwidth and RF output power of unitraveling carrier photodetectors (UTC-PDs). In this work, we report a high-performance UTC-PD featuring a strategically engineered collector layer integrated with such a partially Gaussian doping profile that further optimizes the transport of photo-generated electrons. At a bias of -2.6 V, the proposed structure achieves a 3-dB bandwidth of 54.4 GHz and a peak RF output power of 23.1 dBm at 45 GHz. Compared to UTC-PDs with intrinsic and fully doped collector layers, the 3-dB bandwidth is increased by 25.5 GHz and 20.4 GHz, while the RF output power at 45 GHz is enhanced by 3.4 dBm and 2.3 dBm, respectively. It suggests that bandgap engineering via partially Gaussian doping collector layer is a potent approach for developing the next generation of high-performance photodetector.
SU et al. (Fri,) studied this question.