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Title: Direct observation of the epitaxial growth of molecular layers on molecular single crystals

Abstract

In this letter the authors use the evolution of reflectance anisotropy spectra with film thickness during the growth of organic molecular films of a prototype molecular system ({alpha}-quarterthiophene grown onto a single crystal of the same material) to demonstrate homoepitaxy. The real time monitoring of the optical anisotropy of a thin film during deposition by organic molecular beam epitaxy is assessed as a powerful tool to achieve an effective in situ control of the growth starting from the very early deposition stages.

Authors:
; ; ; ; ; ;  [1];  [2]
  1. Dipartimento di Scienza dei Materiali and CNISM, Universita di Milano-Bicocca, I-20125 Milan (Italy)
  2. (Italy)
Publication Date:
OSTI Identifier:
20880196
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 89; Journal Issue: 26; Other Information: DOI: 10.1063/1.2423322; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANISOTROPY; CRYSTAL GROWTH; DEPOSITION; LAYERS; MOLECULAR BEAM EPITAXY; MONOCRYSTALS; ORGANIC SEMICONDUCTORS; THICKNESS; THIN FILMS

Citation Formats

Sassella, A., Borghesi, A., Campione, M., Tavazzi, S., Goletti, C., Bussetti, G., Chiaradia, P., and Dipartimento di Fisica and CNISM, Universita di Roma 'Tor Vergata', I-00133 Rome. Direct observation of the epitaxial growth of molecular layers on molecular single crystals. United States: N. p., 2006. Web. doi:10.1063/1.2423322.
Sassella, A., Borghesi, A., Campione, M., Tavazzi, S., Goletti, C., Bussetti, G., Chiaradia, P., & Dipartimento di Fisica and CNISM, Universita di Roma 'Tor Vergata', I-00133 Rome. Direct observation of the epitaxial growth of molecular layers on molecular single crystals. United States. doi:10.1063/1.2423322.
Sassella, A., Borghesi, A., Campione, M., Tavazzi, S., Goletti, C., Bussetti, G., Chiaradia, P., and Dipartimento di Fisica and CNISM, Universita di Roma 'Tor Vergata', I-00133 Rome. Mon . "Direct observation of the epitaxial growth of molecular layers on molecular single crystals". United States. doi:10.1063/1.2423322.
@article{osti_20880196,
title = {Direct observation of the epitaxial growth of molecular layers on molecular single crystals},
author = {Sassella, A. and Borghesi, A. and Campione, M. and Tavazzi, S. and Goletti, C. and Bussetti, G. and Chiaradia, P. and Dipartimento di Fisica and CNISM, Universita di Roma 'Tor Vergata', I-00133 Rome},
abstractNote = {In this letter the authors use the evolution of reflectance anisotropy spectra with film thickness during the growth of organic molecular films of a prototype molecular system ({alpha}-quarterthiophene grown onto a single crystal of the same material) to demonstrate homoepitaxy. The real time monitoring of the optical anisotropy of a thin film during deposition by organic molecular beam epitaxy is assessed as a powerful tool to achieve an effective in situ control of the growth starting from the very early deposition stages.},
doi = {10.1063/1.2423322},
journal = {Applied Physics Letters},
number = 26,
volume = 89,
place = {United States},
year = {Mon Dec 25 00:00:00 EST 2006},
month = {Mon Dec 25 00:00:00 EST 2006}
}
  • We have been able to fabricate structures which consist of a thin (approx.10 nm) polycrystalline W film embedded in surrounding single crystalline GaAs by molecular beam epitaxy (MBE) using an electron beam evaporation source to deposit W metal in an ultrahigh vacuum MBE growth chamber. The entire deposition sequence can take place at elevated temperature (625--700 /sup 0/C) due to the nonreactive nature of W with respect to GaAs. Reflective high-energy diffraction and transmission electron microscopy indicate that the single crystal GaAs overgrowth proceeds by seeding from the GaAs layer beneath the W through spontaneously occurring perforations in the Wmore » layer.« less
  • We have been able to fabricate structures which consist of a thin (approx.10 nm) polycrystalline W film embedded in surrounding single crystalline GaAs by molecular beam epitaxy (MBE) using an electron beam evaporation source to deposit W metal in an ultrahigh vacuum MBE growth chamber. The entire deposition sequence can take place at elevated temperature (625--700 /sup 0/C) due to the nonreactive nature of W with respect to GaAs. Reflective high-energy diffraction and transmission electron microscopy indicate that the single crystal GaAs overgrowth proceeds by seeding from the GaAs layer beneath the W through spontaneously occurring perforations in the Wmore » layer.« less
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  • Heavily C-doped p-type GaAs epitaxial films have been grown using carbon tetrabromide (CBr{sub 4}) as a dopant source in both gas source molecular-beam epitaxy (GSMBE) and molecular-beam epitaxy (MBE). It was found that CBr;{sub 4} has a great potential as a p-type dopant source for use in a conventional MBE chamber without any major modification of its pumping system because of its high-doping efficiency and low gas load. Hole concentrations in excess of 1x10{sup 20} cm{sup {minus}3} have been measured in CBr{sub 4}-doped GaAs grown from both the MBE or GSMBE techniques, using As{sub 4} or AsH{sub 3}, respectively. Amore » Hall mobility of > 80 cm{sup 2}/V s was measured in layers with doping level of 5x10{sup 19} cm{sup {minus}3}, which is comparable to that from chemical beam exitaxially (CBE) grown TMGa-doped GaAs. Under GSMBE and MBE modes, the doping memory effect in AlGaAs was greatly reduced using CBr{sub 4} as compared to TMGa doping source. GSMBE grown heterojunction bipolar transistors with a CBr{sub 4} as compared to TMGa doping source. GSMBE grown heterojunction bipolar transistors with a CBr{sub 4}-doped base layer have a current gain as high as 79 and a base sheet resistance as low as 225 {Omega}/{open_square}. 15 refs., 4 figs., 1 tab.« less