Theoretical Investigation of the Gas-Phase Kinetics Active during the GaN MOVPE

Moscatelli, Davide; Cavallotti, Carlo

doi:10.1021/jp068318m

Cited by 26 publications

(29 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, the clusters can also introduce carbon contamination in the layer. Migration away from the substrate leads to further polymerization to eventually form particles up to several hundred nanometers in size. , The particle formation can significantly deplete the precursor flux, thereby reducing the epi-GaN growth rate. − Due to these issues, the adduct pathway is considered as parasitic in GaN MOCVD and therefore to be avoided …”

Section: Gan Mocvd From Tmg and Nh3mentioning

confidence: 99%

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

et al. 2019

View full text Add to dashboard Cite

We report the successful preparation of polycrystalline gallium nitride (poly-GaN) layers by thermal atomic layer deposition (ALD) at low temperatures (375−425°C) from trimethylgallium (TMG) and ammonia (NH 3 ) precursors. The growth per cycle (GPC) is found to be strongly dependent on the NH 3 pulse duration and the NH 3 partial pressure. The pressure dependence makes the ALD atypical. We propose that the ALD involves (i) the reversible formation of the hithertounreported TMG:NH 3 surface adduct, resulting from NH 3 physisorbing on a TMG surface site and (ii) the irreversible conversion of neighboring surface adducts to Ga−NH 2 −Ga linkages. The pressure dependence arises from the presumed reversible nature of the adduct formation on the surface, equivalent to the known reversible nature of its formation in the gas phase in metal organic chemical vapor deposition reactions. Using in situ spectroscopic ellipsometry (SE), the GPC monitored as a function of several ALD parameters is as high as 0.1 nm/cycle at 60 s NH 3 pulse and 1.3 mbar NH 3 partial pressure. The changes in the growth pattern (as monitored by SE) caused by changes in the ALD parameters support the proposed growth model. Ex situ characterization reveals that the layer is carbon-free, has a polycystalline wurtzitic structure, and shows a decent conformaility over Si trenches. Tuning the ALD recipe allows us to vary the layer composition from Ga-rich to stoichiometric GaN. The Ga richness is attributed to the simultaneous TMG dissociation at the deposition temperatures. This work is the first full-scale report on low temperature thermal ALD of poly-GaN from industrial precursors, occurring via a novel chemical pathway and not requiring any radical assistance (such as plasma) as used before.

show abstract

Section: Gan Mocvd From Tmg and Nh3mentioning

confidence: 99%

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

et al. 2019

View full text Add to dashboard Cite

show abstract

“…In the radical mechanism, the initial step is the thermal [27][28][29][30] The formation of dimers and tetramers of Zn(OH) 2 from monomers is energetically possible, but the dehydration reaction, Zn(OH) 2 →ZnO+H 2 O, is too endothermic to take place in the gas phase. 23) This was also confirmed in our present calculations.…”

Section: Discussionmentioning

confidence: 99%

Inference on the Production Mechanism of ZnO Thin Films from Activated Water and Dimethylzinc Molecules

Umemoto

Ishikawa

Nishihara

et al. 2013

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

The reaction of Zn(CH 3) 2 and activated H 2 O produced in a reaction of H 2 and O 2 on a Pt catalyst and effused from a nozzle was examined both experimentally and theoretically. This reaction has been shown to be effective in the preparation of high-quality ZnO films. Laser-induced fluorescence measurements showed that radical species, such as H atoms and OH radicals, do not play major roles. The rotational temperature of H 2 O, measured with a coherent anti-Stokes Raman scattering technique, was 250 K. This low rotational temperature suggests that H 2 O molecules must be accelerated along the beam axis and that the collisional energy between Zn(CH 3) 2 and H 2 O is as high as 43 kJ mol-1. This energy is higher than the potential barrier to produce HOZnCH 3 +CH 4 , 38 kJ mol-1 , obtained by ab initio calculations at the MP2/LANL2DZ level of theory. HOZnCH 3 thus produced can be the strongest candidate ZnO film precursor.

show abstract

“…This could be due to the increased parasitic gas phase reactions facilitated by N radicals (NH 2 ), which form adducts and particles, and consume the precursor supply to the growth surface. [24] Nevertheless, the LA-MOCVD growth technique is a viable approach to achieve fast GR MOCVD GaN with relatively high effective V/III ratio. Surface morphologies of two GaN samples grown on GaN on sapphires templates without and with laser excitation (250 W) were compared.…”

Section: Growth Of La-mocvd Ganmentioning

confidence: 99%

Laser‐Assisted Metal–Organic Chemical Vapor Deposition of Gallium Nitride

Zhang

Chen

Zhang

et al. 2021

Physica Rapid Research Ltrs

View full text Add to dashboard Cite

Ammonia (NH3) is commonly used as group‐V precursor in gallium nitride (GaN) metal–organic chemical vapor deposition (MOCVD). The high background carbon (C) impurity in MOCVD GaN is related to the low decomposition efficiency of NH3, which represents one of the fundamental challenges hindering the development of high‐purity thick GaN for vertical high‐power device applications. This work uses a laser‐assisted MOCVD (LA‐MOCVD) growth technique to address the high‐C issue in MOCVD GaN. A carbon dioxide (CO2) laser with a wavelength of 9.219 μm is utilized to facilitate NH3 decomposition via resonant vibrational excitation. The LA‐MOCVD GaN growth rate (GR; as high as 10 μm h−1) shows a strong linear relationship with the trimethylgallium (TMGa) flow rate, indicating high effective V/III ratios and, hence, efficient NH3 decomposition. [C] in LA‐MOCVD GaN films decreases monotonically, as the laser power increases. A low [C] at 5.5 × 1015 cm−3 is achieved in the LA‐MOCVD GaN film grown with GR of 4 μm h−1. LA‐MOCVD GaN films reveal high crystalline quality with room‐temperature mobility of >1000 cm2 V−1 s−1. LA‐MOCVD provides an enabling route to achieve high‐quality GaN epitaxy with low‐C and fast GR simultaneously. This technique can be extended for epitaxy of other nitride‐based semiconductors.

show abstract

Theoretical Investigation of the Gas-Phase Kinetics Active during the GaN MOVPE

Cited by 26 publications

References 55 publications

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

Inference on the Production Mechanism of ZnO Thin Films from Activated Water and Dimethylzinc Molecules

Laser‐Assisted Metal–Organic Chemical Vapor Deposition of Gallium Nitride

Contact Info

Product

Resources

About