MOCVD

• Metalorganic CVD - uses organic compounds: Ga(CH₃)₃, Ga(C₂H₅)₃ (see picture below)

• Application: Production of III-V materials for LEDs for example
• Advantage - can fabricate abrupt heterojunctions, thin layers at low temperature
• Horizontal or vertical reactors (see picture below)

• Reaction: Ga(CH₃)₃+AsH₃ = GaAs+3CH₄
• AsH₃ is very toxic, thus it was replaced by AsH₂C₄H₉ liquid (TBA)
  • Because this source is liquid, H₂ and N₂ are used for transport
  • Vapor pressure determines the concentration of source material in the reactor and the deposition rate
    • Too low - difficult to transport the source
    • Too high - safety concerns appears because a toxic compound is used
• The final composition of the layer is proportional with the flow ratio
• Vapor pressure determines the deposition rate: , G -growth rate, P -Partial pressure, V- flow rate