I deposited zinc oxy-selenide [Zn(O,Se)] layers by pulsed laser deposition at similar substrate temperature, and deposition time was only one variable parameter. Unexpectedly i got higher Se contents for longer deposition time. The variation of deposition time just affected in film thickness, and the thicker film has higher Se contents. Does any one have an idea about the decrease of Se contents for similar growth temperature, but different thickness?