A delivery device having a first end and a second end, the delivery device comprising: an inlet port; an outlet port; an inlet chamber; and an outlet chamber; the outlet chamber being opposedly disposed to the inlet chamber and in fluid communication with the inlet chamber via a conical section that decreases in cross-section from the first end towards the second end of the delivery device and partially separates the inlet chamber from the outlet chamber; the outlet chamber comprising a labyrinth that is operative a) to prevent particles of a solid precursor compound contained in the delivery device from leaving the delivery device while at the same time permitting vapors of the solid precursor compound to leave the delivery device via the outlet port, and b) to cause a carrier gas travelling from the inlet port to the outlet port to make two or more turns, each turn being through an average angle of greater than or equal to about 120 degrees, the turns being measured with respect to an average direction of travel prior to making the turn; wherein the labyrinth is formed by a restrictor, the conical section and an inner wall of the delivery device, where a portion of the conical section protrudes through a plane that includes a surface of the restrictor, and where a height (h 1) of the restrictor is greater than a height (h 2) of the conical section taken at its smallest diameter when measured from a floor or from a roof of the outlet chamber. an inlet port; an outlet port; an inlet chamber; and an outlet chamber; the outlet chamber being opposedly disposed to the inlet chamber and in fluid communication with the inlet chamber via a conical section that decreases in cross-section from the first end towards the second end of the delivery device and partially separates the inlet chamber from the outlet chamber; the outlet chamber comprising a labyrinth that is operative a) to prevent particles of a solid precursor compound contained in the delivery device from leaving the delivery device while at the same time permitting vapors of the solid precursor compound to leave the delivery device via the outlet port, and b) to cause a carrier gas travelling from the inlet port to the outlet port to make two or more turns, each turn being through an average angle of greater than or equal to about 120 degrees, the turns being measured with respect to an average direction of travel prior to making the turn; a) to prevent particles of a solid precursor compound contained in the delivery device from leaving the delivery device while at the same time permitting vapors of the solid precursor compound to leave the delivery device via the outlet port, and b) to cause a carrier gas travelling from the inlet port to the outlet port to make two or more turns, each turn being through an average angle of greater than or equal to about 120 degrees, the turns being measured with respect to an average direction of travel prior to making the turn; wherein the labyrinth is formed by a restrictor, the conical section and an inner wall of the delivery device, where a portion of the conical section protrudes through a plane that includes a surface of the restrictor, and where a height (h 1) of the restrictor is greater than a height (h 2) of the conical section taken at its smallest diameter when measured from a floor or from a roof of the outlet chamber.