Continuous compositional grading for realization of low charge carrier barriers in electro-optical heterostructure semiconductor devices

Abstract

Processes and devices for continuous compositional grading in photodetectors and electro-absorption modulators (EAM) are provided. An example photodetector includes a multi-layered structure comprising a collector region, an absorber region, a grading layer, and a peripheral layer, all aligned along a detection axis. The grading layer, positioned adjacent to the absorber region, includes multiple sub-layers that define a continuous compositional grading to facilitate smooth carrier transport and reduce recombination. Similarly, an example electro-absorption modulator (EAM) device includes a waveguide mesa formed on a semiconductor substrate, comprising a multi-quantum well (MQW) core layer, upper and lower near-core cladding layers, and upper and lower central cladding layers. The EAM device features both upper and lower grading layers, each positioned between the near-core cladding layers and the adjacent central cladding layers. These grading layers include multiple sub-layers that define a continuous compositional grading, facilitating smooth transitions between the MQW core and surrounding cladding layers.

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