Laser-induced selective area band-gap tuning in $Si/Si1−xGex$ microstructures

A one-step process is reported for selective area band-gap tuning of as-grown quantum well (QW) material consisting of $Si/Si1−xGex$ microstructures. The process takes advantage of the ability of increasing the local temperature of the wafer, in excess of $900 °C,$ by applying the beam of a high-power cw Nd:YAG laser, which leads to controlled intermixing between the quantum well and barrier material. A microstructure with the band-gap blueshifted by 142 meV has been fabricated from as-grown 980 meV band-gap material. The results indicate that this approach has the potential for “writing” of $Si/Si1−xGex$ QW microstructures with the selectively tuned band gap required in the fabrication of optoelectronic integrated circuits.