Growth of AlGaN epitaxial layers and AlGaN/GaN superlattices by metal-organic chemical vapor deposition

Review—Review of Research on AlGaN MOCVD Growth

“…However, when adding TMAl/III in the second way afterward, the Al increased linearly with TMAl/III. The same conclusion was obtained in the experiment of Lundin et al 52 and Kim et al 40 The phenomenon was attributed to that the parasitic reaction between TMAl and NH 3 was stronger than TMGa, and more consumption of TMAl was caused by parasitic reaction, without effect on the layer growth, when the flow rate of TMAl was large. As a result, lowering the TMGa fux was more effective than increasing the TMAl flow rate to raise the Al component in the layer.…”

“…4b. 39,40,42,50,51,48,[52][53][54] All results indicated that the Al component decreased with pressure, which was attributed to the fact that the increased parasitic reaction of TMAl and NH 3 led to a large consumption of Al source due to rising pressure. Significantly, under the low pressure range (<150 torr), the Al component decreased rapidly with increasing pressure, which was especially prominent in the research of Touzi et al, 53 while the decline was slow under middle and high pressure range (>150 torr).…”

“…However, when the ammonia content is high, the strong parasitic reaction enhances the gas-phase scavenging effect of the Al source on the Ga source and the etching effect of H 2 on GaN by NH 3 decomposition, 17,[70][71][72] eventually resulting in the consumption of the source gas. 47 Bao et al 73 and Lundin et al 52 studied the effect of carrier gas H 2 on the growth of AlGaN, and found that the growth rate and the Al component in the layer increased with the rise of carrier gas flow rate, and then they tended to be saturate at high flow rate. In conclusion, increasing the gas flow rate was favorable for suppressing the parasitic reaction and raising the growth rate.…”

“…The simulation revealed that in the lower reaction chamber, the nanoparticles were less and only existed in the inlet area of low temperature, thus the parasitic reaction could be suppressed greatly. Comparing the horizontal small-sized reactor VP-50RP and the large-size reactor AIX2000HT 52,75 , Lundin et al found that the Al component in the layer tended to saturate as the flow rate of TMAl rose during the growth in the this two reactors, which was more pronounced in the AIX2000HT reactor. However, there was no accurate reason for this phenomenon.…”

Competing reactions during metalorganic deposition: Ligand-exchange versus direct reaction with the substrate surface

“…8 and 88) and In, 8 have received considerable attention for the deposition schemes of the respective metals. 97,98 In most cases, appropriate set of deposition conditions can be selected to yield conformal, contaminant-free films with these precursors. 97,98 In most cases, appropriate set of deposition conditions can be selected to yield conformal, contaminant-free films with these precursors.…”