Methods of depositing compound semiconductor materials on one or more substrates include metering and controlling a flow rate of a precursor liquid from a precursor liquid source into a vaporizer. The precursor liquid may comprise at least one of GaCl3, InCl3, and AlCl3 in a liquid state. The precursor liquid may be vaporized within the vaporizer to form a first precursor vapor. The first precursor vapor and a second precursor vapor may be caused to flow into a reaction chamber, and a compound semiconductor material may be deposited on a surface of a substrate within the reaction chamber from the precursor vapors. Deposition systems for performing such methods include devices for metering and/or controlling a flow of a precursor liquid from a liquid source to a vaporizer, while the precursor liquid remains in the liquid state.