(Invited) Plasma-Enhanced Atomic Layer Deposition of III-Nitride Thin Films

Abstract

AlN and GaN thin films were deposited by plasma-enhanced atomic layer deposition using trimethylmetal precursors. The films were found to have high oxygen incorporation, which was attributed to oxygen contamination related to the plasma system. The choice of nitrogen containing plasma gas (N 2 , N 2 /H 2 or NH 3 ) determined the severity of oxygen incorporation into deposited films. Lowest oxygen concentrations were attained for AlN and GaN thin films using NH 3 and N 2 plasma, respectively. Initial experiments have shown that GaN thin films with low impurity concentrations can be deposited when plasma-related oxygen contamination is avoided by the use of an alternative plasma source.

Hollow cathode plasma-assisted atomic layer deposition of crystalline AlN, GaN and AlxGa1−xN thin films at low temperatures

“…We observed similar results for the AlN and GaN lms deposited using the previous conguration with a quartz-based ICP source, 49 where the use of N 2 plasma resulted in high concentrations of C and O impurities in the deposited lms and destroyed crystallinity. The presence of C impurities (8.0 and 9.1 at.% for AlN and GaN, respectively) 49 suggests that the organic ligands are trapped inside the growing lm since N 2 plasma without any H 2 is not efficient in terms of removing the ligands of the chemisorbed trimethylmetal precursors. This might be avoided at higher temperatures, where the methyl ligands of the precursor molecules get free by self-decomposition.…”

Optical characteristics of nanocrystalline AlxGa1−xN thin films deposited by hollow cathode plasma-assisted atomic layer deposition

“…6 Thin films of GaN, AlN, and their alloys have been deposited by a variety of deposition processes including sputtering, 7,8 metal-organic chemical vapor deposition (MOCVD), [9][10][11] plasma enhanced-CVD, 12 molecular beam epitaxy (MBE), 13,14 and atomic layer deposition (ALD). [15][16][17] During the last decade, numerous papers have been published on the deposition of epitaxial layers of GaN, AlN, and their alloys using both the MOCVD and MBE methods. Nevertheless, while, high quality epitaxial films of these nitrides can be deposited by MOCVD and MBE at high temperatures (800-1000 C), the low-temperature deposition methods are needed as well for next generation device applications including CMOS-compatible III-nitride device integration and potential durable flexible optoelectronics.…”

Hollow-cathode plasma-assisted atomic layer deposition: A novel route for low-temperature synthesis of crystalline III-nitride thin films and nanostructures

“…The source of this O contamination was found to be related to the sputtering of quartz tube of the ICP source. In view of these circumstances, the choice of N-containing plasma gas (N 2 , N 2 /H 2 or NH 3 ) determined the severity of O incorporation into the deposited thin films [10]. In order to avoid this contamination problem, we integrated a stainless steel hollow cathode plasma (HCP) source to the ALD system, and thereby reported the hollow cathode PA-ALD (HCPA-ALD) of nanocrystalline AIN and GaN thin films with low impurity concentrations at 200 °C using trimethylmetal precursors [11].…”

“…%) for ~2 min, then rinsed with DI water and dried with N 2 . The details regarding to the preparation of electrospun nylon 6,6 nanofiber templates are given elsewhere [10].…”