LIGHT MODULATORS COMPRISING SI-GE QUANTUM WELL LAYERS

摘要

Optical modulators include active quantum well structures (200) coherent with pseudosubstrates (100) comprising relaxed buffer layers (104, 106, 108, 110) on a silicon substrate (102). In a preferred method the active structures, consisting of Si1-x Gex barrier and well layers with different Ge contents x, are chosen in order to be strain compensated. The Ge content in the active structures may vary in a step-wise fashion along the growth direction or in the form of parabolas within the quantum well regions. Optical modulation may be achieved by a plurality of physical effects, such as the Quantum Confined or Optical Stark Effect, the Franz-Keldysh Effect, exciton quenching by hole injection, phase space filling or temperature modulation. In a preferred method the modulator structures are grown epitaxially by low-energy plasma-enhanced chemical vapor deposition (LEPCVD).