Gallium Nitride (GaN) is an important wide-gap (3.4 eV) semiconductor with applications in opto-and power electronics. It offers excellent chemical durability and a high breakdown field strength. The high optical transparency and chemical stability of GaN make it a suitable material for solar cells. All of these applications require the deposition of GaN thin layers or films. An emerging technique for thin GaN films is atomic layer deposition (ALD), a technique based on sequential delivery of gaseous reactant molecules to the surface of a heated substrate where surface chemical reactions deposit, ideally, one atomic layer. The film growth self-limits after the chemical reactions have consumed all available surface sites. The reactor is then purged before introducing the subsequent precursor onto the substrate to deposit a layer of a second type of atoms . The most common gallium precursors are the tri-alkyl metal molecules, trimethylgallium (TMG), and triethylgallium (TEG) , and Ammonia (NH3), with or without plasma activation, or nitrogen plasma, are common nitrogen precursors. It has been shown that GaN deposited using TMG exhibits better optical and structural properties than GaN deposited using TEG. The very high vapor pressure of TMG makes it challenging to use in ALD, where the precursor vapor is typically drawn by low pressure in the reactor. Therefore, the use of TMG requires either valves that can open for a very short time or cooling of the TMG container.