The　crystallization　processes　of　Si-Sb　thin　films　containing　different　amounts　of　Si　were　investigated　by　in　situ　transmission　electron　microscopy　(thermal　annealing　and　electron　beam　irradiation).　It　was　found　that　increase　in　the　Si　content　significantly　improve　the　thermal　stability　of　SixSb100-x　thin　films　and　changes　the　crystallization　behaviour　from　growth-dominated　to　nucleation-dominated,　thus　leading　to　the　refinement　of　the　grain　size.　Further　analysis　shows　that　phase　separation　occurs　if　the　Si　content　increases　by　more　than　18.1%,　resulting　in　the　coexistence　of　high-Si　amorphous　regions　and　low-Si　crystalline　regions.　Our　results　suggest　a　critical　Si　content,　below　which　phase　separations　can　be　prevented.　(C)　2012　Elsevier　B.V.　All　rights　reserved.