High power bottom-emitting In0.2Ga0.8As/GaAs 4*4 two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays, with high output power in the 980-nm wavelength regime are reported. At room temperature, the 16-element array with 200-micron aperture size of individual elements shows a continuous wave output power of 1.21 W with a lasing wavelength of 981.9 nm. Temperature dependent characteristics of VCSEL arrays with 90-micron aperture size of individual elements are investigated. The lasing wavelength, optical output power and threshold current are measured at various heatsink temperatures. With the increase of heatsink temperature, the maximum output power and slope efficiency are greatly decreased. A red shift of lasing wavelength and a widening of the lasing spectrum are also observed.