An Integrated Photodetector Based on a Modulation-Doped Heterostructure

An optically active heterostructure field effect transistor (HFET) structure is described as a three terminal detector. With an in-plane waveguide optical input it demonstrates natural optoelectronic integration with transistors. Both depletion and enhancement threshold devices are realized with photocurrent enhancement of the HFET current of 1.72 for direct coupling. A simple model of photocurrent generation based on bipolar operation provides good agreement. The bidirectional response may be suitable for optical gating functions in balanced detection.