A　comparative　study　on　crystallization　characteristics　of　amorphous　Ge2Sb2Te5　(GST)　films　induced　by　an　ultraviolet　pulse　laser　and　isothermal　annealing　was　carried　out　by　using　transmission　electron　microscopy　(TEM)　and　Raman　scattering.　TEM　observations　showed　that　the　mean　grain　size　induced　by　a　pulse　laser　was　in　the　nanoscale.　A　more　complete　crystallization　in　the　50　nm　thick　GST　film　was　obtained　which　was　ascribed　to　the　effect　of　thermal　convection　produced　in　a　thinner　GST　film,　however,　when　the　film　thickness　was　over　70　nm,　no　significant　decrease　in　the　mean　grain　size　was　found　because　of　the　effect　of　heating　mode,　where　a　surface　heat　source　by　the　ultraviolet　laser　radiation　caused　a　quick　temperature　drop.　The　body　heating　mode　at　the　isothermal　annealing　condition　made　the　mean　grain　size　increase　remarkably　with　the　increase　of　film　thickness,　which　could　be　up　to　the　submicron　scale,　relative　to　the　size　of　film　thickness.　The　Raman　spectrum　analysis　showed　that　a　red　shift　was　observed　in　laser　induced　Ge2Sb2Te5　films　as　compared　to　the　isothermal　annealing　samples,　which　was　caused　by　the　resultant　stress　of　the　thermal　stress　and　phase　transformation　stress.　(C)　2015　Elsevier　B.V.　All　rights　reserved.