A metal-organic chemical vapor deposition (MOCVD) system is provided for high throughput processing. The system comprises a chamber containing a substrate support system comprising a plurality of substrate support planets operable to support one or more substrates, and a gas emission system operable to provide a plurality of isolated environments suitable for depositing uniform layers on the substrates. The MOCVD system is operable to independently vary one or more process parameters in each isolated environment, and to provide common process parameters to all substrates for depositing one or more layers on all substrates. Methods of forming uniform layers on a substrate are provided wherein at least one of the layers is deposited in an isolated environment.