Quantum Chemistry Study on Gas Reaction Mechanism in AlN MOVPE Growth

Zhang, Hong; Zuo, Ran; Zhong, Tingting; Lian, Zhang

doi:10.1021/acs.jpca.9b11817

Cited by 8 publications

(2 citation statements)

References 24 publications

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“…As per a previous report, the adduct formation is unavoidable at TMAl reaction with NH 3 during the HT-MOCVD process 10 , 11 . A state of Al–N chemical compound, which is a typical source for AlN growth, is not ideal.…”

Section: Introductionsupporting

confidence: 75%

Reduction of parasitic reaction in high-temperature AlN growth by jet stream gas flow metal–organic vapor phase epitaxy

Nagamatsu

Tsuda

Miyagawa

et al. 2022

Sci Rep

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AlGaN-based deep ultraviolet light-emitting diodes (LEDs) have a wide range of applications such as medical diagnostics, gas sensing, and water sterilization. Metal–organic vapor phase epitaxy (MOVPE) method is used for the growth of all-in-one structures, including doped layer and thin multilayers, using metal–organic and gas source raw materials for semiconductor devices. For AlN growth with high crystalline quality, high temperature is necessary to promote the surface migration of Al atoms and Al-free radicals. However, increase in temperature generates parasitic gas-phase prereactions such as adduct formation. In this work, AlN growth at 1500 °C by a stable vapor phase reaction has been achieved by jet stream gas flow metal–organic vapor phase epitaxy. The AlN growth rate increases with gas flow velocity and saturates at ~ 10 m/s at room temperature. Moreover, it is constant at an ammonia flow rate at a V/III ratio from 50 to 220. These results demonstrate the reduction in adduct formation, which is a typical issue with the vapor phase reaction between triethylaluminum and ammonia. The developed method provides the in-plane uniformity of AlN thickness within 5%, a low concentration of unintentionally doped impurities, smooth surface, and decrease in dislocation density because of the suppression of parasitic reactions.

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Section: Introductionsupporting

confidence: 75%

Reduction of parasitic reaction in high-temperature AlN growth by jet stream gas flow metal–organic vapor phase epitaxy

Nagamatsu

Tsuda

Miyagawa

et al. 2022

Sci Rep

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show abstract

“…This finding can be elucidated by two phenomena shown below. Rising temperatures cause a parasitic reaction in the vapor phase, which is a phenomena [23][24][25][26][27] . The TMA raw material may accelerate the reaction with ammonia during transit by increasing the growth temperature 28 .…”

mentioning

confidence: 99%

High growth temperature for AlN by jet stream gas flow metalorganic vapor phase epitaxy

Nagamatsu

Miyagawa

Tomita

et al. 2023

Sci Rep

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Deep ultraviolet light-emitting diodes have attracted considerable attention for realizing virus inactivation applications. The UV-LEDs use the AlN underlying layer and the plane sapphire substrate. However, the low growth temperature in AlN underlying layer is grown by limited growth temperature in conventional MOVPE, and high temperature is preferable for AlN growth. Furthermore, the AlN underlying layer has many dislocations owing to the active layer in the device region when the flat sapphire substrate was used with a dislocation value of > 109 cm−2. We showed the high-temperature crystal growth of AlN with a temperature of 1700 °C by high temperature and gas flow velocity MOVPE. The achieved dislocation density was ~ 4 × 108 cm−2. Additionally, this data means the low dislocation densities in the AlN layer with a growth time of only 15 min and a dislocation density of < 1 × 109 cm−2 are obtained. The AlN growth temperature exceeding 1550 °C decreases the growth rate. These results indicate desorption from the surface of the substrate in a hydrogen atmosphere. Furthermore, the characteristic dislocation behavior of AlN in high-temperature growth at 1700 °C was elucidated from TEM images.

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Estimation of Junction Temperature in Single 228 nm‐Band AlGaN Far‐Ultraviolet‐C Light‐Emitting Diode on c‐Sapphire Having 1.8 mW Power and 0.32% External Quantum Efficiency

Ajmal Khan,

Muta,

Fujimoto

et al. 2024

Physica Status Solidi (a)

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The increasing resistance of methicillin‐resistant Staphylococcusaureus to antibiotics is a major challenge faced by mankind in thehistory of medical science and according to United Nations, 700‐000 patients worldwide die every year from an infection with multidrug‐resistant organisms (MROs). Aluminum gallium nitride‐based 228 nm Far‐ultraviolet‐C (Far‐UVC) lightsources can be safely used as a germicidal application in both manned as wellas in unmanned environments against these MROs. Previously, the 228 nm Far‐UVC light‐emitting diode (LED) with emission power of 1 mW was reported by ourgroup, however, the value of external quantum efficiency (EQE) was not reportedusing conventional thick Ni (20 nm)/Au (100 nm) p‐electrode. Herein, animproved Far‐UVC LED on c‐Sapphire is attempted using a special technique in SR4000 type of metal‐organic chemical vapor deposition reactor to control the Al composition in n‐AlGaN buffer and across the 2 inch‐wafer. As a result, the light emission power of 1.8 mW and EQE of 0.32% in 228 nm Far‐UVC LED aresuccessfully achieved using very thin p‐electrode (Ni/Au). However, arelatively high junction temperature of ≈100°C around thejunction of Far‐UVC LED is observed. Finally, some simple heat‐sink modules forheat dissipation of Far‐UVC LED panel with light power of 30 mW are implemented.

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Quantum Chemistry Study on Gas Reaction Mechanism in AlN MOVPE Growth

Cited by 8 publications

References 24 publications

Reduction of parasitic reaction in high-temperature AlN growth by jet stream gas flow metal–organic vapor phase epitaxy

Reduction of parasitic reaction in high-temperature AlN growth by jet stream gas flow metal–organic vapor phase epitaxy

High growth temperature for AlN by jet stream gas flow metalorganic vapor phase epitaxy

Estimation of Junction Temperature in Single 228 nm‐Band AlGaN Far‐Ultraviolet‐C Light‐Emitting Diode on c‐Sapphire Having 1.8 mW Power and 0.32% External Quantum Efficiency

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