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

Abstract

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.

(Invited) Recent Progress in Wide-Bandgap Semiconductor Devices for a More Electric Future

“…OSU found the NH 3 molecules are most efficiently decomposed with the CO 2 laser excitation at 9.219 µm. OSU demonstrated growth rates as high as 10 µm /hr with a pit free surface morphology (16). The strong linear relationship of the GaN growth rate to the TMGa flow rate in the LA-MOCVD process indicate high effective V/III ratios due to efficient NH decomposition.…”

Suppressing Carbon Incorporation in Metal–Organic Chemical Vapor Deposition GaN Using High‐Offcut‐Angled Substrates

“…The increase in the active N‐species concentration suppresses C incorporation, since there are more active N‐species that can be readily incorporated into the lattice. [ 20 ] The reduction in C incorporation in LA‐MOCVD GaN has proven to be extremely effective, with suppression in C concentrations ([C]) of up to 87%. [ 11 ]…”

“…The increase in the active N-species concentration suppresses C incorporation, since there are more active N-species that can be readily incorporated into the lattice. [20] The reduction in C incorporation in LA-MOCVD GaN has proven to be extremely effective, with suppression in C concentrations ([C]) of up to 87%. [11] From the prior theoretical studies on C suppression using high-offcut-angle GaN substrates and experimental demonstration on the effective suppression of C in LA-MOCVD GaN, it is promising to greatly reduce C incorporation in MOCVD GaN using the combination of LA-MOCVD growth technique and GaN substrates with high offcut angles.…”

Synthesis and characterization of GaN/quartz nanostructure using pulsed laser ablation in liquid

“…Several research have tried to make GaN nanostructures utilizing different growing processes, such as metalorganic chemical vapor deposition [27], reactive molecular beam epitaxy [28], thermal ammonization [29,30], physical vapor deposition (PVD) [31,32], chemical vapor deposition [33], sol-gel chemistry [34], electrochemical deposition (ECD) [35], thermal vapor deposition [36], and pulsed laser deposition (PLD) [3,37]. High heat and expensive chemicals are major drawbacks of these processes, resulting in a low production yield.…”