Three-dimensional　(3D)　topological　insulators　(TIs)　are　candidate　materials　for　various　electronic　and　spintronic　devices　due　to　their　strong　spin-orbit　coupling　and　unique　surface　electronic　structure.　Rapid,　low-cost　preparation　of　large-area　TI　thin　films　compatible　with　conventional　semiconductor　technology　is　the　key　to　the　practical　applications　of　TIs.　Here　we　show　that　wafer-sized　Bi2Te3　family　TI　and　magnetic　TI　films　with　decent　quality　and　well-controlled　composition　and　properties　can　be　prepared　on　amorphous　SiO2/Si　substrates　by　magnetron　cosputtering.　The　SiO2/Si　substrates　enable　us　to　electrically　tune　(Bi1-xSbx)(2)Te-3　and　Cr-doped　(Bi1-xSbx)(2)Te-3　TI　films　between　p-type　and　n-type　behavior　and　thus　study　the　phenomena　associated　with　topological　surface　states,　such　as　the　quantum　anomalous　Hall　effect　(QAHE).　This　work　significantly　facilitates　the　fabrication　of　TI-based　devices　for　electronic　and　spintronic　applications.