Quantitative time-resolved observations of ground-state zinc atoms, methyl radicals, and excited CH radicals resulting from the 193 nm photodissociation of dimethylzinc

Abstract

The ArF laser photodissociation dynamics of dimethylzinc at 193 nm have been studied, and their implications for the growth of ZnSe thin films are discussed. A broadband, vacuum ultraviolet argon plasma emission has been used to acquire time-resolved absorption profiles from ground-state Zn atoms and methyl radicals. Time-resolved fluorescence from excited CH radicals has also been studied. The results indicate that the Zn concentration remains constant from 100 ns to 2 ms after the dissociating ArF pulse, indicating that this system is a good source for free Zn atoms. The CH3 radicals are formed immediately after the dissociation pulse and recombine within several hundred microseconds to form ethane. There was no indication of monomethylzinc (MMZn) formation, and the detected CH radical is likely to combine with H2 to form CH3 within several microseconds. This implies that the major sources for carbon contamination in the growth process (CH3, MMZn, CH) are unlikely to reach the growth surface.