Identification of the dissociative and kick-out diffusion mechanisms of Zn diffusion in GaAs by photoluminescence analysis

• Zn diffusion in GaAs differs when Zn/Ga alloy is used instead of Zn/As alloy.
• Ga atoms could suppress the high-concentration surface region of the Zn profile.
• Photoluminescence analysis was used to identify the diffusion mechanisms.
• Ga vacancies were found in the surface region of the kink-and-tail profile.
• Ga vacancy was not found in the box profile and the tail of kink-and-tail profile.

Most investigations on Zn diffusion in GaAs were processed using the Zn–As alloy sources to prevent the As atoms from escaping GaAs wafers, while we found that the Zn diffusion would change fundamentally if Zn–Ga alloy sources were used. The Ga atoms from the diffusion sources suppressed the formation of the high-concentration surface region in Zn profiles, thus converting a kink-and-tail profile into a box profile. The photoluminescence (PL) analysis was used to identify the diffusion mechanisms. The Ga vacancy defects were found in the surface region of the kink-and-tail profile, indicating that the dissociative mechanism dominated; the PL spectrum in the tail region of kink-and-tail profile and the main region of box profile showed the same signals, no Ga vacancy defects were found, thus the kick-out mechanism dominated.