Influence of microstructure on electrical properties of diluted GaNxAs1−x formed by nitrogen implantation

Journal of Applied Physics

Scarpulla

et al. 2003

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We present a systematic investigation on the formation of the highly mismatched alloy GaN x As 1-x using N + -implantation followed by a combination of pulsed laser melting and rapid thermal annealing. Thin films of GaN x As 1-x with x as high as 0.016 and an activation efficiency of the implanted N up to 50% have been synthesized with structural and optical properties comparable to films grown by epitaxial deposition techniques with similar substitutional N content. The effects of N + implantation dose, laser energy fluence and rapid thermal annealing temperature on the N incorporation as well as optical and structural properties of the GaN x As 1-x films are discussed.

Section: Crystalline Structure Of N + -Implanted Gaas Layers Processementioning

confidence: 92%

Section: Nitrogen Activation Efficiencymentioning

confidence: 99%

Synthesis of GaNxAs1−x thin films by pulsed laser melting and rapid thermal annealing of N+-implanted GaAs

Journal of Applied Physics

Scarpulla

et al. 2003

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“…37 Such a drastic improvement can be attributed to the extremely short melt duration (~2×10 -7 s) and re-growth process that promotes N substitution in the As site and inhibits the formation of nitrogen related voids. 38 In addition to the enhanced N incorporation, the dilute nitride layers synthesized by N + -implantation followed by PLM-RTA were also found to be thermally stable up to annealing temperature >950°C. This improved sample synthesis technique provides a convenient and reliable method, in addition to conventional epitaxial growth techniques, 2,4,12 for preparing large variety of dilute nitride samples.…”

Section: Samplesmentioning

confidence: 99%

“…In the course of optimizing the annealing conditions in these studies, it was found that, in GaNAs formed in this way, the substitutional N As is thermally unstable at temperatures higher than 850°C and will precipitate to form N-related voids. 38 Most recently, we have shown that pulsed laser melting (PLM) of N-implanted III-Vs dramatically improves the incorporation of N on the group-V element site. 39,40 In PLM, the near surface absorption of a single intense laser pulse instantaneously melts the implant-damaged or amorphized layer.…”

Section: Samplesmentioning

confidence: 99%

Band anticrossing in dilute nitrides

Shan

J. Phys.: Condens. Matter

et al. 2004

Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states.The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.

“…The value of the band gap of the laser melted layers does not change significantly even at RTA temperature of 950ºC, suggesting that the substitutional nitrogen (N As ) in these layers appears are thermally stable. We speculate that the extremely short duration of the laser melting and regrowth process inhibits the formation of nitrogen related voids, which have recently been observed in samples formed by N + -implantation followed by RTA only [24]. The process of rapid melting and solidification may result in a complete local rearrangement of the atom sites leading to the formation of strong Ga-N bonds, thus stabilizing N atoms on the anion sites.…”

mentioning

confidence: 99%

Enhanced nitrogen incorporation by pulsed laser annealing of GaNxAs1−x formed by N ion implantation

Applied Physics Letters

Beeman

et al. 2002

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We demonstrate that pulsed laser annealing followed by rapid thermal annealing greatly enhances incorporation of substitutional N in N + -implanted GaAs. Films implanted to 1.8% N exhibit a fundamental band gap of 1.26eV (a band gap reduction of 160meV), corresponding to an N activation efficiency of 50%. The optical and crystalline quality of the synthesized film is comparable to GaN x As 1-x thin films of similar composition grown by epitaxia l growth techniques. Compared to films produced by N + implantation and rapid thermal annealing only, the introduction of pulsed laser annealing improves N incorporation by a factor of five. Moreover, we find that the synthesized films are thermally stable up to an annealing temperature of 950ºC.