Surface reaction mechanism in MOMBE-ALE of ZnSe and CdSe as determined by a new in-situ optical probing method

The surface reaction mechanism in MOMBE-ALE of ZnSe and CdSe using DMZn, DMCd and H2Se as reactants has been studied with a newly developed optical in-situ monitoring method named surface photo-interference (SPI). It is shown that there is a quite significant difference in the surface reaction mechanism between the MOMBE-ALE of ZnSe and CdSe. That is, in the ALE of ZnSe when none of the source gases are pre-cracked, the reaction to form ZnSe can take place when the group-II source (i.e., DMZn) is supplied, resulting in an alternate appearance of Zn-terminated and H2Se-terminated surfaces during growth. On the other hand, the reaction to form CdSe can take place when a group-VI source (i.e., H2Se) is supplied, resulting in an alternate appearance of Se-terminated and DMCd-terminated surfaces during growth.