Mechanism of the photochemically induced reaction between Ga(CH3)3 and HN3 and the deposition of GaN films

Abstract

Gaseous HN3 reacts with surface-bound Ga(CH3)x species slowly at 300 K to produce thin films containing azide-substituted gallium compounds. When mixtures of HN3 and Ga(CH3)3 over the surface are irradiated at 253.7 nm, the reaction is dramatically accelerated, and films containing GaN and complexed N2 are produced. Heating of these films to 400 K drives off the N2 leaving GaN. The mechanism of the reaction is thought to involve photodissociation of HN3 to produce excited NH(a1Δ) and N2, followed by insertion of the NH(a1Δ) into the Ga–C bond of surface-bound Ga(CH3)x molecules. The insertion product eliminates CH4 to leave GaN.

Materials Chemistry of Group 13 Nitrides

“…When gaseous mixtures of HN 3 and GaMe 3 over the substrate are irradiated at λ = 253.7 nm, the reaction is dramatically accelerated and GaN films are obtained at 400 K. The mechanism of the reaction is thought to involve NH species that insert into Ga -C bonds at the surface. The insertion products eliminate CH 4 to leave GaN [115,116]. The triazides M(N 3 ) 3 of aluminum, gallium, and indium would undoubtedly meet some of the above criteria for good single-molecule nitride precursors.…”

“…The interaction of AlMe 3 with HN 3 in the gas phase has been shown to produce Al(N 3 ) 3 , which deposits as a thin film on the walls of the reaction vessel. These thin films were heated to 400 K and amorphous AlN was obtained [115,116]. The reaction of gaseous HN 3 with surface-bound GaMe x species gives azidesubstituted gallium compounds at the surface.…”

Growth kinetics of GaN thin films grown by OMVPE using single source precursors

“…Many efforts have been undertaken to substitute the ineffective nitrogen source (NH 3 ) using alternative precursors based on the concept of preformed direct M-N bonds in the precursor molecule. Such precursors for the growth at a lower V/III ratio and milder growth conditions were achieved with many compounds for instance hydrazine (N 2 H 4 ), 1-1-dimethyl hydrazine (M 2 NNH 2 ), phenyl hydrazine (PhNH-NH 2 ), hydrazoic acid (HN 3 ) [6][7][8] and also alkyl amines (RNH 2 , R = t Bu, i Pr) [9] . But the disadvantages of these precursors are their toxic and explosive nature as well as carbon incorporation into the resulting films.…”

Laser-Assisted Room-Temperature Film Growth Using a Constrained Pulsed Nozzle Expansion

“…As ablation sources, excimer lasers in particular have found utility as a means of generating thin films, a good example being the production of superconducting films − In our research group, a longstanding goal has been to use lasers in understandable ways, not only to study laser-assisted chemical reactivity but to correlate this reactivity with thin-film properties. One motivation for the work is to discover routes by which true room-temperature growth conditions can be achieved when metalorganic precursors are used.…”

“…(2) The effects of the laser can be readily monitored with respect to photoactivation as well as subsequent reactivity, i.e., the formation of new com- plexes in the expansion. (3) The deposition of the films can be correlated with laser-induced reactivity within the expansion. (4) The method is general and can be applied to a number of precursor systems including two, three, and four component mixtures.…”