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The relationship between the purge time and the overall growth rate in pulsed injection metal–organic chemical vapor deposition with different V/III ratios is studied by numerical analysis. The transport behavior of TMAl and TMAlNH₃ during the process is studied to understand the effect of the adductive reaction. The results show that, as the V/III ratio increases, there is a significant reduction in the average growth rate per cycle, without the addition of a purging H₂ pulse between the III and V pulses, due to stronger adductive reaction. The adductive reaction can be reduced by inserting a purging pulse of pure H₂ between the III and V pulses, but there is a decrease in the overall growth rate due to the longer cycle time. At smaller V/III ratios, the growth rate decreases with increasing purge times, since the gain in reducing the adductive reaction is offset by the detrimental effect of extending the cycle time. The degree of reduction in the adductive reaction is higher for larger V/III ratios. When the benefit of reducing the adductive reaction overcomes the deficiency of the extending cycle time, a remarkable enhancement of the growth rate can be obtained at high V/III ratios by inserting a pure H₂ purge pulse between the III and V pulses. A higher overall growth rate can be achieved at higher V/III ratios by choosing an appropriate purge time.