Analysis of pulsed injection of precursors in AlN‐MOVPE growth by computational fluid simulation

Abstract

We report computational analysis of gas‐phase states and main reaction pathways under AlN metalorganic vapor‐phase epitaxy (MOVPE) by pulsed injection (PI) method of precursors. Interval times of 0–2 s were inserted between trimethylaluminum (Al(CH3); TMAl) and ammonia (NH3) supply phases to suppress parasitic reactions. In the cases of the interval time of 0 s, polymers and Al‐N molecules were dominant species due to parasitic reaction, and the growth species was Al‐N molecules generated by TMAl:NH3 pyrolysis. When an interval time was inserted between TMAl and NH3, mixing of TMAl and NH3 were suppressed. Al and NH2 generated from each precursor were dominant species. The main reaction pathway changed from TMAl:NH3 pyrolysis into TMAl pyrolysis with increasing the interval time. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Simulation of Nitride Semiconductor MOVPE

“…Therefore, the growth surface will have high and low V/III ratio modes alternatively. Such flow modulation in MOVPE presumably suppresses the formation of adducts and their polymerization [49]. Therefore, the current reaction pathways for the MOVPE of GaN, InGaN, AlN, and AlGaN are valid for calculating the flow modulation MOVPE because the growth paths will be selected automatically by the precursors' feeding methods.…”

Chemical Reaction Pathways for MOVPE Growth of Aluminum Nitride

“…However, the contribution of molecules derived from the parasitic reactions of AlN growth remains unclear, although several kinetic models that consider an AlN growth pathway through adduct-related molecules have been developed. [7][8][9] Therefore, in the present study, we investigated the possibility of a chemical reaction pathway through the TMA-NH 3 adduct using elementary reaction simulations and DFT calculations.Elementary reaction simulations were carried out to determine the reactive species using a kinetic model for AlN growth reported by Mihopoulos et al 9 The basic concept of this growth mechanism is similar to that described by Creighton and Wang. 6 The kinetic model has 10 gas-phase and 7 surface reactions.…”

“…However, the growth rate is generally limited by parasitic chemical reactions initiated by trimethyl-aluminum (TMA) and ammonia (NH 3 ) precursors. [3][4][5][6][7][8] Creighton and Wang 6 investigated the early stages of the reaction between TMA and NH 3 using IR spectroscopy and density functional theory (DFT) calculations. They reported a parasitic reaction mechanism in which a TMA-NH 3 adduct was first formed and subsequently decomposed into amide and methane, finally producing amide oligomers.…”

Review—Review of Research on AlGaN MOCVD Growth

“…In the process of MOCVD pulse growth of AlN, there will be Al-rich or Nrich conditions as mentioned above. 146 Nevertheless, there is barely any research conducted into the surface of AlGaN ternary alloys so far, and the effect of Al component on the surface stability of AlGaN ternary alloys remains unclear. Furthermore, the surface reaction of the growth precursor on the surface of AlGaN is still unclear.…”