Trimethyl gallium (TMG)

Description

Trimethyl gallium (TMG)

Chemical identity

• Formula: Ga(CH3)3
• Molar mass: ≈ 115 g/mol
• Structure: Gallium atom tetrahedrally coordinated to three methyl groups; a typical organogallium precursor used in semiconductor processing.

What it is used for

• A key organometallic precursor in MOVPE/MOCVD growth processes for gallium-containing semiconductors.
• Commonly employed to deposit Ga-containing layers in materials such as GaAs and related compounds.

Basic properties

• TMG is a volatile, moisture-sensitive organometallic compound.
• It is typically used under inert conditions and can be supplied as a gas or as a solution in an inert solvent.
• Exact physical properties (state at room temperature, boiling point, etc.) can vary with grade and handling conditions; it is generally considered to be highly reactive with air and water.

Synthesis (general overview)

• TMG can be prepared by alkylating gallium halides with methylating agents. A representative reaction is:
  • GaCl3 + 3 CH3Li → Ga(CH3)3 + 3 LiCl
• Other methylating methods (e.g., using methyl Grignard reagents) are also used in practice.
• Handling is typically done under strictly inert, anhydrous conditions.

Handling and safety

• Very reactive with air and moisture: reacts vigorously, releasing methane and forming gallic or oxide/hydroxide species.
• Pyrophoric: can ignite spontaneously in air if not properly contained.
• Store and handle under an inert atmosphere (e.g., nitrogen or argon) using a glovebox or Schlenk techniques.
• Use appropriate personal protective equipment, work in a well-ventilated area with proper fire protection, and follow the supplier’s MSDS guidelines.
• Avoid contact with water, oxygen, and oxidizers.

Alternatives and related compounds

• Triethyl gallium (TEGa) is another commonly used Ga precursor in MOVPE/MOCVD.
• The choice between TMG and alternatives depends on growth conditions, desired film quality, and reactor compatibility.

Notes and limitations

• If you require exact physical properties (boiling point, vapor pressure at a given temperature, etc.), consult the material safety data sheet (MSDS) or supplier datasheet for the specific grade you are using.
• I can provide a comparison table or example process parameters if you’re planning a deposition or reaction setup.