H, C, and O impurity concentrations in metalorganic chemical vapor dep
osition grown InGaN were found to be dependent on the hydrogen and NH3
flow rates. By increasing the hydrogen flow rate from O to 100 seem,
a decrease of greater than two orders of magnitude in the C and O impu
rity levels and one order of magnitude in the H impurity level was obs
erved. Increasing the NH3 flow rate from 1 to 5 sim results in a decre
ase in the C concentration and an increase in the H and O concentratio
ns indicating that high purity NH3 (99.999%) can be a significant sour
ce of O contamination. Additional studies show that when the InN perce
nt in the InGaN films increases, the impurity concentrations increase
regardless of changes in the growth conditions. The InGaN films were g
rown from 710 to 780 degrees C and the impurity concentrations were ch
aracterized by secondary ion mass spectrometry. (C) 1997 American Inst
itute of Physics.