Influence of the exchange reaction on the electronic structure of GaN/Al junctions

S. Picozzi*, A. Continenza, S. Massidda, A. J. Freeman, N. Newman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Ab initio full-potential linearized augmented plane-wave (FLAPW) calculations have been used to study the influence of the interface morphology and, notably, of the exchange reaction on the electronic properties of Al/GaN (100) interfaces. Although the detailed mechanism is not understood, the exchange reaction has been purported to influence the Schottky barrier height (SBH) as a result of the formation of an interfacial GaxAl1-xN layer. In particular, the effects of interface structure (i.e., interfacial bond lengths, semiconductor surface polarity, and reacted intralayers) on the SBH at the Al/GaN (001) junction are specifically addressed. Thus, the electronic structure of the following atomic configurations have been investigated theoretically: (i) an abrupt, relaxed GaN/Al interface; (ii) an interface that has undergone one monolayer of exchange reaction; and interfaces with a monolayer-thick interlayer of (iii) AlN and (iv) Ga0.5Al0.5N. The exchange reaction is found to be exothermic with an enthalpy of 0.1 eV/atom. We find that the first few layers of semiconductor are metallic due to the tailing of metal-induced gap states; therefore, the presence of a monolayer-thick interfacial alloy layer does not result in an enhanced band gap near the interface. Intermixed interfaces are found to pin the interface Fermi level at a position not significantly different from that of an abrupt interface. Our calculations also show that the interface band lineup is not strongly dependent on the interface morphology changes studied. The p type SBH is reduced by less than 0.1 eV if the GaN surface is Ga terminated compared to the N terminated one. Moreover, we show that both an ultrathin GaxAl1-xN (x = 0, 0.5) intralayer and a Ga↔Al atomic swap at the interface do not significantly affect the Schottky barrier height.

Original languageEnglish
Pages (from-to)7906-7912
Number of pages7
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume58
Issue number12
StatePublished - Sep 15 1998

ASJC Scopus subject areas

  • Condensed Matter Physics

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