Photonic integration of InGaAs-InGaAsP laser using low energy implantation induced quantum well intermixing

Neutral impurity induced quantum well intermixing (QWI) is an attractive and promising postgrowth bandgap engineering process for the fabrication of photonic integrated circuits (PICs), as it introduces no additional electrical active dopants into the material system after intermixing. Here, we report the development of neutral impurity induced QWI processes in InGaAs-InGaAsP laser structure using low energy, i.e. 360 keV, arsenic and phosphorous ion implantation. The samples were implanted at room temperature and 200 °C, with a dose range between 10¹² and 10¹⁴ ions/cm². The QWI stage was carried out by annealing the implanted samples at 650 °C for 120 s. Samples implanted at 200 °C give higher degree of QWI. Compared to P implanted samples, larger bandgap shift was observed from As implanted samples after annealing. A differential PL bandgap shift as large as 93 nm (60 meV) was observed from samples implanted with 10¹⁴ ions/cm² of AS. Bandgap tuned lasers fabricated from intermixed samples; the current threshold density of the intermixed lasers slowly increases with the amount of blueshift and is kept below 20% for the most blueshifted devices. The attractive device characteristics of the bandgap tuned lasers show that damage induced by the ion implantation can be almost fully treated after annealing. This implies that the material remains in good quality after QWI.