A study of parasitic reactions between NH3 and TMGa or TMAI

The growth of AlGaN using organametallic vapor phase epitaxy has been studied as a function of reactor pressure in a horizontal reactor. At atmospheric pressure, GaN with growth efficiency comparable to that of GaAs in the same reactor is obtained. In addition, the GaN growth efficiency changes little at different reactor pressures. These results indicate that the parasitic reaction between TMGa and NH3 is not substantial in the reactor used in this study. On the other hand, AIN growth at atmospheric pressure has not been possible. By lowering the reactor pressure below 250 Torr, AIN deposition is achieved. However, the growth efficiency decreases at higher reactor pressures and and higher growth temperatures; indicating that a strong parasitic reaction occurs between TMA1 and NH3. For the ternary AlGaN, lower pressure also lends to more Al incorporation. The results indicate that parasitic reactions are much more severe for TMA1+NH3 than for TMGa+NH3.