Improved p-doping profiles in lasers and modulators

Zn diffusion during MOCVD growth is studied in a series of different structures using SIMS analysis. A first experiment supports a concentration dependent diffusion rate, and a +1 charge on the Zn interstitial. The Zn diffusion front is found to be quite sharp, and this is used advantageously in combination with an undoped spacer layer in a p-i-n structure. Further experiment explores the effect of p+ InGaAs caps (both C and Zn doped) on the diffusion in underlying p to undoped (p-i) interfaces, and find that there is minimal impact.