InP-Based Double-Heterostructure Phototransistors with an Optical-Gain Cutoff Frequency of 135 GHz

We present a high-speed-layer- and process compatible phototransistor based on our InP-based double-heterostructure bipolar transistor (DHBT) technology. By using only the base and a thin base-collector spacer as absorption layer, slow drifting holes in the collector layer are avoided. This results in record optical-gain cutoff frequencies of up to 135 GHz at the expense of intrinsic photodiode responsivity in a top-illuminated configuration.