Provided are methods of forming a more highly-oriented silicon thin layer having a larger grain size, and a substrate having the same. The methods may include forming an aluminum (Al) layer on a base substrate, forming a more highly-oriented Al layer by recrystallizing the Al layer under vacuum, forming a more highly-oriented .gamma.-Al.sub.2O.sub.3 layer on the more highly-oriented Al layer and/or epitaxially growing a silicon layer on the more highly-oriented .gamma.-Al.sub.2O.sub.3 layer. The method may be used to manufacture a semiconductor device having higher carrier mobility.