We　fabricated　InGaZnO　(IGZO)　ceramic　target　(In:　Ga:　Zn　=　1:　1:　4　in　atomic　ratio)　using　solid-state　reaction　at　ambient　atmosphere,　and　deposited　IGZO　thin　films　on　quartz　glass　at　room　temperature　under　various　oxygen　partial　pressures　using　the　pulsed　laser　deposition　method.　Influence　of　oxygen　pressure　on　crystal　structure,　surface　morphology,　optical　and　electrical　properties　were　investigated.　It　was　found　that　all　the　films　deposited　at　room　temperature　exhibit　amorphous　structure.　On　the　other　hand,　the　physical　properties　of　the　films　like　transparency,　electron　mobility,　and　free-electron　concentration　were　found　to　be　correlated　to　the　oxygen　pressure　during　the　deposition　and　in　turn　to　the　possible　oxygen　vacancies　or　metallic　interstitials　in　the　films.　The　analysis　of　X-ray　photoelectron　spectra　(XPS)　of　the　films　indicated　that　there　are　no　metallic　3d　states　of　In,　Ga　and　Zn,　suggesting　that　oxygen　vacancies　could　be　main　defects　that　affect　physical　properties　of　the　films.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.