Generation of atomic hydrogen during radio-frequency nitrogenplasma-assisted gas-source molecular-beam epitaxy of III-V dilute nitrides

Abstract

The interaction of a typical gas-source molecular-beam epitaxy (GSMBE) environment with a radio-frequency (RF) nitrogen plasma source is investigated. In particular, a real-time in situ analysis of the evolution of the emission spectrum of an RF nitrogen plasma source, under high partial pressures of hydrogen (∼10−5Torr), is presented. Hydrogen, emanating from the decomposition of hydride precursors in GSMBE, results in the appearance of a sharp emission peak at the region of 656nm in the plasma spectrum, suggesting the generation of atomic hydrogen species in the nitrogen plasma cavity. The intensity of this peak is used for a qualitative evaluation of this interaction and its evolution as a function of the RF nitrogen plasma source conditions is investigated.

Effect of residual hydrogen and temperature on initial growth stages and properties of GaAs1−xNx

“…Details of the growth system utilized are given elsewhere [11][12][13]. We experimentally determined that the critical thickness for lattice relaxation for GaAsN epilayers grown on GaAsN with N content below 1.8% was above 1200-1300 Å , and for that reason all samples in this study were fabricated at a constant thickness of 1100 Å .…”

“…It has been demonstrated that in these methods the presence of a high partial pressure of residual hydrogen, a byproduct of the decomposition of hydride precursors and from the use of H 2 as a carrier gas for organometallic (OM) precursors, during the growth of III-V dilute nitrides leads to the formation of atomic hydrogen species in the plasma discharge tube [12,13] indicated by the appearance of a sharp emission line at $656 nm that matches the wavelength of the H a line of the hydrogen atom (H a is the first term of the Balmer series). The presence of this line, the intensity of which increases linearly with the partial pressure of hydrogen in the plasma tube [12], indicates the diffusion of residual hydrogen from the growth chamber into the rf plasma discharge tube and the consequent formation of atomic hydrogen species. The formation of atomic hydrogen species in the rf plasma source could lead to the incorporation of atomic hydrogen in the grown epilayer and thus to the potential modification of the properties of the fabricated material.…”

Near band-edge luminescence and evidence of the weakening of the N-conduction-band coupling for partially relaxed and high nitrogen composition GaAs1−xNx epilayers

“…The ratio of atomic versus molecular nitrogen species as well as the rf plasma spectral signature were recorded real time during the growth process. 17,18 The substitutional nitrogen composition and the residual strain magnitude ͑relaxation state͒ in epilayers were extracted by analyzing the symmetric ͑004͒ and asymmetric ͕115͖ reflections of the high resolution x-ray diffraction ͑XRD͒ rocking curves. The growth conditions and structural analysis of these epilayers are reported elsewhere.…”

Formation of atomic hydrogen during radio frequency nitrogen plasma assisted chemical beam epitaxy of III–V dilute nitrides

“…24 This hydrogen-induced emission indicates a retro diffusion of residual hydrogen from the CBE growth chamber into the plasma discharge tube, which leads to the formation of active hydrogen species. 25 It should be noted that higher order terms of the Balmer series ͑H ␤ = 486 nm, H ␥ = 434 nm, ….͒ as well as emissions from nitrogen ionic species occur beyond the transparency window of the PBN discharge tube of the plasma source.…”