Understanding Indium Nitride Thin Film Growth Under ALD Conditions by Atomic Scale Modelling: From the Bulk to the In-Rich Layer

Damas, Giane B.; Rönnby, Karl; Pedersen, Henrik; Ojamäe, Lars

doi:10.2139/ssrn.3982949

Cited by 1 publication

(7 citation statements)

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“…Additional routes are also considered to account for the possibility of DMI formation 22,39 from the i) radical attack on TMI; ii) direct TMI-TMI collision or iii) reaction with H radicals in a H-rich environment in Mech 3-5:…”

Section: 1-trimethylindiummentioning

confidence: 99%

“…This step is assumed to release methane (CH4) through the reaction between the Hcontaining plasma (from NH3 decomposition) and chemisorbed methylindium (MI), which constitutes the presumed final point of the half-cycle towards the In-rich layer formation. 10,38,39 The remaining NH2 radicals should then undergo chemisorption to form a NH2-terminated surface, whereas eventual NH radicals are not expected to be a frequent specimen at the conditions that are typical of an ALD experiment. 38 In the next half-cycle, the TMI insertion into the gas chamber is primarily thought to lead to its physisorption onto the NH2-terminated surface, in which the dipole-dipole interaction occurs through the p-empty orbital (from TMI) and a lone pair (from NH2).…”

Section: -Introductionmentioning

confidence: 99%

“…38 In the next half-cycle, the TMI insertion into the gas chamber is primarily thought to lead to its physisorption onto the NH2-terminated surface, in which the dipole-dipole interaction occurs through the p-empty orbital (from TMI) and a lone pair (from NH2). 38,39 Nonetheless, Hwang et al 40 have employed in situ-Raman spectroscopy to verify that the TMI decomposition in gas phase is feasible at T= 120 -535 °C, in N2 environment, in a process that is characterized by the homolytic dissociation into the MI precursor and CH3 radicals that quickly recombine into ethane (C2H6). [40][41][42][43] The In-rich layer formation onto the NH2-terminated surface could then be achieved through a reaction mechanism involving the adsorption of i) TMI in an intact form, 39 ii) dimethylindium (DMI) 22,39 or iii) MI, 22,39 where ii) and iii) involve precursor decomposition in gas phase.…”

Section: -Introductionmentioning

confidence: 99%

“…38,39 Nonetheless, Hwang et al 40 have employed in situ-Raman spectroscopy to verify that the TMI decomposition in gas phase is feasible at T= 120 -535 °C, in N2 environment, in a process that is characterized by the homolytic dissociation into the MI precursor and CH3 radicals that quickly recombine into ethane (C2H6). [40][41][42][43] The In-rich layer formation onto the NH2-terminated surface could then be achieved through a reaction mechanism involving the adsorption of i) TMI in an intact form, 39 ii) dimethylindium (DMI) 22,39 or iii) MI, 22,39 where ii) and iii) involve precursor decomposition in gas phase. On the other hand, the surface-driven decomposition in i) exhibits lower activation barriers that should favor the deposition rate.…”

Section: -Introductionmentioning

confidence: 99%

“…On the other hand, the surface-driven decomposition in i) exhibits lower activation barriers that should favor the deposition rate. 39 Another precursor for ALD and conventional chemical vapor deposition (CVD) of In2O3, 44,45 with potential use in InN deposition, 23,46 is tris(N,N′-diisopropyl-2-dimethylamidoguanidinato (III) (ITG). This molecule pertains to a class of precursors where the indium atom (In) is surrounded by three bidentate ligands with In-N bonds.…”

Section: -Introductionmentioning

confidence: 99%

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Thermal Decomposition of Trimethylindium and Indium Trisguanidinate Precursors for InN Growth: An Ab-Initio and Kinetic Modelling Study

Damas¹,

Rönnby

Pedersen

et al. 2023

Preprint

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Indium nitride (InN) is an interesting material for future electronic and photonic-related applications, as it combines high electron mobility and low-energy band gap for photoabsorption or emission-driven processes. In this context, atomic layer deposition (ALD) techniques have been previously employed for InN growth at low temperatures (typically < 350 C), reportedly yielding crystals with high quality and purity. In general, this technique is assumed to not involve any gas phase reactions as a result from the time-resolved insertion of volatile molecular sources into the gas chamber. Nonetheless, such temperatures could still favour the precursor decomposition in gas phase during the In half-cycle, therefore altering the molecular species that undergoes physisorption and, ultimately, driving the reaction mechanism to pursue other pathways. Thence, we herein evaluate the thermal decomposition of relevant In precursors in gas phase, namely trimethylindium (TMI) and tris(N,N-diisopropyl-2-dimethylamido-guanidinato) (III) (ITG), by means of thermodynamic and kinetic modelling. According to the results, at T= 593 K, TMI should exhibit partial decomposition of ~8% after 400 s to first generate methylindium (MI) and ethane (C2H6), a percentage that increases to ~34% after 1 hour of exposure inside the gas chamber. Therefore, this precursor should be present in an intact form to undergo physisorption during the In half-cycle of the deposition experiment (< 10 s). On the other hand, the ITG decomposition starts already at the temperatures used in the bubbler and it will slowly decompose as it is evaporated during the deposition process. At T= 300 C, the decomposition is a fast process that reaches 90% completeness after 1 s, and where equilibrium, at which almost no ITG remains, is achieved before 10 s. In this case, the decomposition pathway is likely to occur via elimination of carbodiimide ligand. Ultimately, these results should contribute for a better understanding of the reaction mechanism involved in the InN growth from these precursors.

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Section: 1-trimethylindiummentioning

confidence: 99%