Single-layer structure supporting both heterojunction bipolar transistor and surface-normal modulator
An n-p-i(shallow quantum well)-n GaAs-AlGaAs layer structure has been produced from which either heterojunction bipolar transistors (HBTs) or surface-normal modulators may be fabricated, allowing single-growth integration of those devices for optical interconnects. The shallow quantum well region provides large electroabsorption while having no impedance to electron transport. The HBTs have a gain of 15. The modulators have a change in transmission from 30.7 percent to 50.1 percent for a change in bias from +1 V to -3 V.