Metal organic vapour phase epitaxy of AlN, GaN, InN and their alloys: a key chemical technology for advanced device applications

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Abstract

This article reviews metal organic vapour phase epitaxy (MOVPE) processes developed for the group 13 nitrides AlN, GaN, InN and their alloys. The binaries are direct-gap semiconductors with respective bandgaps of 6.1 eV for AlN, 3.4 eV for GaN, and ∼0.6 eV for InN, and adopt the hexagonal wurtzite crystal structure. The nitrides form continuous solid solutions, and are capable of being both n- and p-doped, thus making possible the growth of advanced heterostructure devices exemplified by GaN-based visible light-emitting diodes. Interest in nitride MOVPE from the late 1980s motivated significant work on single-source precursors, and also thermally labile nitrogen sources for use in two-source processes. The best developed of the former are azido compounds, which can have properties well tailored for low-temperature film deposition. However, the nitride MOVPE processes that have come to dominate device manufacturing since the mid-1990s depend on the reaction between ammonia and metal alkyl sources, and deposit GaN at temperatures usually above 1000 °C. Most current nitride growth is performed heteroepitaxially on sapphire (0 0 0 1) substrates, for which appropriate multistep growth initiation processes have been optimised. Current designs of nitride MOVPE reactor are engineered to avoid premature contact between the group 13 sources and ammonia, and feature in situ monitoring by optical means. The mechanisms of the growth chemistry are now understood to the extent that they are handled explicitly in multi-scale computational simulations of full processes. Particular recent advances in mechanistic understanding concern the role of nanoparticles that form in the gas phase, and which represent an important precursor loss channel. Methodologies for controlling the composition and properties of layers of GaN itself, and of ternary alloy layers with moderate (<25 mole%) contents of InN or AlN, are well established. However, greater challenges are posed by growth of layers InN, AlN, and of alloys close to these two binaries in composition. New variants of MOVPE continue to be explored as a consequence, and include processes with pulsed alternating precursor introduction to enhance lateral migration of adatoms on the surface of the growing film. A further important new emphasis in recent years is the controlled growth of nanowire and nanorod arrays, which already include core-shell heterostructures of considerable sophistication.
LanguageEnglish
Pages2120-2141
Number of pages22
JournalCoordination Chemistry Reviews
Volume257
Issue number13-14
Early online date8 Nov 2012
DOIs
Publication statusPublished - 31 Jul 2013

Fingerprint

Vapor phase epitaxy
vapor phase epitaxy
Nitrides
Metals
metal nitrides
metals
nitrides
Ammonia
Heterojunctions
ammonia
Ternary alloys
Adatoms
Aluminum Oxide
ternary alloys
Film growth
Chemical analysis
Nanorods
Sapphire
wurtzite
adatoms

Keywords

  • indium nitride
  • light-emitting diode
  • metal organic vapor phase epitaxy
  • metal organic chemical vapor deposition
  • gallium nitride
  • aluminum nitride

Cite this

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title = "Metal organic vapour phase epitaxy of AlN, GaN, InN and their alloys: a key chemical technology for advanced device applications",
abstract = "This article reviews metal organic vapour phase epitaxy (MOVPE) processes developed for the group 13 nitrides AlN, GaN, InN and their alloys. The binaries are direct-gap semiconductors with respective bandgaps of 6.1 eV for AlN, 3.4 eV for GaN, and ∼0.6 eV for InN, and adopt the hexagonal wurtzite crystal structure. The nitrides form continuous solid solutions, and are capable of being both n- and p-doped, thus making possible the growth of advanced heterostructure devices exemplified by GaN-based visible light-emitting diodes. Interest in nitride MOVPE from the late 1980s motivated significant work on single-source precursors, and also thermally labile nitrogen sources for use in two-source processes. The best developed of the former are azido compounds, which can have properties well tailored for low-temperature film deposition. However, the nitride MOVPE processes that have come to dominate device manufacturing since the mid-1990s depend on the reaction between ammonia and metal alkyl sources, and deposit GaN at temperatures usually above 1000 °C. Most current nitride growth is performed heteroepitaxially on sapphire (0 0 0 1) substrates, for which appropriate multistep growth initiation processes have been optimised. Current designs of nitride MOVPE reactor are engineered to avoid premature contact between the group 13 sources and ammonia, and feature in situ monitoring by optical means. The mechanisms of the growth chemistry are now understood to the extent that they are handled explicitly in multi-scale computational simulations of full processes. Particular recent advances in mechanistic understanding concern the role of nanoparticles that form in the gas phase, and which represent an important precursor loss channel. Methodologies for controlling the composition and properties of layers of GaN itself, and of ternary alloy layers with moderate (<25 mole{\%}) contents of InN or AlN, are well established. However, greater challenges are posed by growth of layers InN, AlN, and of alloys close to these two binaries in composition. New variants of MOVPE continue to be explored as a consequence, and include processes with pulsed alternating precursor introduction to enhance lateral migration of adatoms on the surface of the growing film. A further important new emphasis in recent years is the controlled growth of nanowire and nanorod arrays, which already include core-shell heterostructures of considerable sophistication.",
keywords = "indium nitride, light-emitting diode, metal organic vapor phase epitaxy, metal organic chemical vapor deposition, gallium nitride, aluminum nitride",
author = "Watson, {Ian M.}",
year = "2013",
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T2 - Coordination Chemistry Reviews

AU - Watson, Ian M.

PY - 2013/7/31

Y1 - 2013/7/31

N2 - This article reviews metal organic vapour phase epitaxy (MOVPE) processes developed for the group 13 nitrides AlN, GaN, InN and their alloys. The binaries are direct-gap semiconductors with respective bandgaps of 6.1 eV for AlN, 3.4 eV for GaN, and ∼0.6 eV for InN, and adopt the hexagonal wurtzite crystal structure. The nitrides form continuous solid solutions, and are capable of being both n- and p-doped, thus making possible the growth of advanced heterostructure devices exemplified by GaN-based visible light-emitting diodes. Interest in nitride MOVPE from the late 1980s motivated significant work on single-source precursors, and also thermally labile nitrogen sources for use in two-source processes. The best developed of the former are azido compounds, which can have properties well tailored for low-temperature film deposition. However, the nitride MOVPE processes that have come to dominate device manufacturing since the mid-1990s depend on the reaction between ammonia and metal alkyl sources, and deposit GaN at temperatures usually above 1000 °C. Most current nitride growth is performed heteroepitaxially on sapphire (0 0 0 1) substrates, for which appropriate multistep growth initiation processes have been optimised. Current designs of nitride MOVPE reactor are engineered to avoid premature contact between the group 13 sources and ammonia, and feature in situ monitoring by optical means. The mechanisms of the growth chemistry are now understood to the extent that they are handled explicitly in multi-scale computational simulations of full processes. Particular recent advances in mechanistic understanding concern the role of nanoparticles that form in the gas phase, and which represent an important precursor loss channel. Methodologies for controlling the composition and properties of layers of GaN itself, and of ternary alloy layers with moderate (<25 mole%) contents of InN or AlN, are well established. However, greater challenges are posed by growth of layers InN, AlN, and of alloys close to these two binaries in composition. New variants of MOVPE continue to be explored as a consequence, and include processes with pulsed alternating precursor introduction to enhance lateral migration of adatoms on the surface of the growing film. A further important new emphasis in recent years is the controlled growth of nanowire and nanorod arrays, which already include core-shell heterostructures of considerable sophistication.

AB - This article reviews metal organic vapour phase epitaxy (MOVPE) processes developed for the group 13 nitrides AlN, GaN, InN and their alloys. The binaries are direct-gap semiconductors with respective bandgaps of 6.1 eV for AlN, 3.4 eV for GaN, and ∼0.6 eV for InN, and adopt the hexagonal wurtzite crystal structure. The nitrides form continuous solid solutions, and are capable of being both n- and p-doped, thus making possible the growth of advanced heterostructure devices exemplified by GaN-based visible light-emitting diodes. Interest in nitride MOVPE from the late 1980s motivated significant work on single-source precursors, and also thermally labile nitrogen sources for use in two-source processes. The best developed of the former are azido compounds, which can have properties well tailored for low-temperature film deposition. However, the nitride MOVPE processes that have come to dominate device manufacturing since the mid-1990s depend on the reaction between ammonia and metal alkyl sources, and deposit GaN at temperatures usually above 1000 °C. Most current nitride growth is performed heteroepitaxially on sapphire (0 0 0 1) substrates, for which appropriate multistep growth initiation processes have been optimised. Current designs of nitride MOVPE reactor are engineered to avoid premature contact between the group 13 sources and ammonia, and feature in situ monitoring by optical means. The mechanisms of the growth chemistry are now understood to the extent that they are handled explicitly in multi-scale computational simulations of full processes. Particular recent advances in mechanistic understanding concern the role of nanoparticles that form in the gas phase, and which represent an important precursor loss channel. Methodologies for controlling the composition and properties of layers of GaN itself, and of ternary alloy layers with moderate (<25 mole%) contents of InN or AlN, are well established. However, greater challenges are posed by growth of layers InN, AlN, and of alloys close to these two binaries in composition. New variants of MOVPE continue to be explored as a consequence, and include processes with pulsed alternating precursor introduction to enhance lateral migration of adatoms on the surface of the growing film. A further important new emphasis in recent years is the controlled growth of nanowire and nanorod arrays, which already include core-shell heterostructures of considerable sophistication.

KW - indium nitride

KW - light-emitting diode

KW - metal organic vapor phase epitaxy

KW - metal organic chemical vapor deposition

KW - gallium nitride

KW - aluminum nitride

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DO - 10.1016/j.ccr.2012.10.020

M3 - Article

VL - 257

SP - 2120

EP - 2141

JO - Coordination Chemistry Reviews

JF - Coordination Chemistry Reviews

SN - 0010-8545

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ER -