The role of hydrogen in the process of successive laser crystallization of hydrogenated amorphous silicon

Abstract Amorphous films containing hydrogen have been crystallized by employing a combined laser dehydrogenation/crystallization technique. Structural changes during the successive crystallization were detected by Raman measurements. The dehydrogenation was monitored by secondary ion mass spectroscopy and by measuring the Si–HX stretching vibrations using Raman spectroscopy. In the course of successive crystallization a two layer system is created with a crystallized layer on top of an amorphous layer. Experimentally obtained threshold laser energy densities of crystallization confirm theoretical predictions. During the laser dehydrogenation the vibrational band at 2000 cm−1 decreases faster than the vibrational band at ∼2080 cm−1. Secondary ion mass spectroscopy measurements show that fully crystallized films still contain hydrogen concentrations ⩽5 at. %.