Growth Optimization of an Electron Confining InN/GaN Quantum Well Heterostructure |
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Authors: | E Dimakis E Iliopoulos M Kayambaki K Tsagaraki A Kostopoulos G Konstantinidis A Georgakilas |
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Affiliation: | (1) Microelectronics Research Group, Physics Department, University of Crete, 71003 Heraklion-Crete, Greece;(2) Institute of Electronic Structure and Lasers, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece |
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Abstract: | The molecular beam epitaxy of In-face InN (0001) epilayers with optimized surface morphology, structural quality, and electrical
properties was investigated. Namely, compact InN epilayers with atomically flat surfaces, grown in a step-flow mode, were
obtained using stoichiometric fluxes of In and N and substrate temperatures in the range from 400°C to 435°C. Typical values
for the electron concentration and the Hall mobility at 300 K were 4.3 × 1018 cm−3 and 1210 cm2/Vs, respectively. The growth mode of InN during the very first stage of the nucleation was investigated analytically, and
it was found that the growth proceeds through nucleation and fast coalescence of two-dimensional (2-D)–like InN islands. The
preceding conditions were used to grow an InN/GaN quantum well (QW) heterostructure, which exhibited well-defined interfaces.
Schottky contacts were successfully fabricated using a 15-nm GaN barrier enhancement cap layer. Capacitance-voltage measurements
revealed the confinement of electrons within the InN QW and demonstrated the capability to modulate the electron density within
an InN channel. The sheet concentration of the confined electrons (1.5 × 1013 cm−2) is similar to the calculated sheet polarization charge concentration (1.3 × 1013 cm−2) at the InN/GaN interface. However, electrons may also originate from ionized donors with a density of 8 × 1018 cm−3 within the InN layer. |
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Keywords: | Molecular beam epitaxy nitrides InN heterostructure electron confinement |
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