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ISSN - 09214526, Physica B: Condensed Matter, 2009, vol. 404, p. 4870-4872

Electrical properties and deep traps spectra in AlGaN films with nitrogen and gallium polarities prepared by molecular beam epitaxy

Protasov D. Yu, Tereshchenko O. E., Zhuravlev K. S., Polyakov A. Y., Smirnov N. B., Govorkov A. V.

Electrical properties and deep traps spectra of Ga-face and N-face AlGaN films with Al mole fraction ranging from 0 to 0.6 were studied by means of current voltage, capacitance-voltage measurements, deep traps transient spectroscopy, admittance spectroscopy, photoluminescence spectroscopy. The films were grown by molecular beam epitaxy using a combined buffer consisting of a low temperature AlN nucleation layer and AlGaN/GaN superlattice. The polarity of the film is determined by whether the low temperature AlN is grown under the nitrogen-rich (promotes N-polarity) or Al-rich (promotes Ga-polarity) conditions. It shown that the Ga-face samples grown in this fashion have highly compensated p-type conductivity with the dominant acceptors being similar to standard acceptor species in GaN. For N-face films the conductivity is n-type and the dominant donors can be attributed to Si. The density of deep traps was found to be much higher for the N-face samples compared to the Ga-face samples. © 2009 Elsevier B.V. All rights reserved.