Enhanced Impurity-Free Intermixing Bandgap Engineering for InP-Based Photonic Integrated Circuits

Impurity-free intermixing of InGaAsP multiple quantum wells (MQW) using sputtering Cu/SiO₂ layers followed by rapid thermal processing (RTP) is demonstrated. The bandgap energy could be modulated by varying the sputtering power and time of Cu, RTP temperature and time to satisfy the demands for lasers, modulators, photodetector, and passive waveguides for the photonic integrated circuits with a simple procedure. The blueshift of the bandgap wavelength of MQW is experimentally investigated on different sputtering and annealing conditions. It is obvious that the introduction of the Cu layer could increase the blueshift more greatly than the common impurity free vacancy disordering technique. A maximum bandgap blueshift of 172 nm is realized with an annealing condition of 750°C and 200 s. The improved technique is promising for the fabrication of the active/passive optoelectronic components on a single wafer with simple process and low cost.