Tunable Schottky barriers and the nature of Si interface layers in Al/GaAs(001) diodes

Abstract

Articles you may be interested inStudy on the interfaces of Cu/PA-N and PA-N/Si by secondary ion mass spectroscopy and scanning electron microscopy J.Effect of Al ion implantation on the adhesion of Al films to SiO2 substrates High-temperature stable Ir-Al/n-GaAs Schottky diodes: Effect of the barrier height controlling Silicon layers grown by molecular beam epitaxy in the interface region of Al/n-GaAs͑001͒ Schottky diodes have been shown to tune the Schottky barrier height in the 0.3-1.1 eV range, provided that high enough excess fluxes of As or Al are employed during Si deposition. We studied the incorporation of As and Al in the interface layer for Si growth temperatures of 300 and 400°C, and for interlayer thicknesses in the 10-150 Å range. Following deposition under an excess As flux we found an As atomic concentration c As ϭ0.4 -0.5 at 300°C and c As ϭ0.2 at 400°C. The excess Al flux yielded an Al atomic concentration c Al ϭ0.7-0.8 at 300°C, and c Al ϭ0.6 -0.7 at 400°C. Correspondingly, the lattice structure of the interlayers appears dramatically different from that of Si. We conclude that the 10-100 Å interface layers used by some authors to change the barrier height bear little resemblance to degenerate bulk Si, so that several of the mechanisms proposed to explain Schottky barrier tuning should be reevaluated.

Schottky barrier tuning with heterovalent interlayers: Al/Ge/GaAs versus Al/Si/GaAs

“…1 It has been shown, moreover, that the lattice structures of the interlayers with thicknesses above 10 Å bear no resemblance to that of bulk Si. 13 As such structures are beyond the scope of our present first-principles investigations, and since we expect similar trends for Ge interlayers, we will not attempt to discuss here the behavior of the barriers at high interlayer coverage. Nevertheless, it is interesting to note that, similarly to the trend predicted by the ab initio calculations at low coverage, the measurements on Ge interlayers at high coverage indicate a reduction in the amplitude of the barrier variations relative to the Si case, for interlayers having comparable thicknesses.…”

Unpinning of the Au/GaAs interfacial Fermi level by means of ultrathin undoped silicon interlayer inclusion

“…Of recent decade, tuning of Schottky barrier height ͑SBH͒ in a quite wide interval has been achieved via ultrathin, preferably heavily doped silicon interlayers inserted between the semiconductor and metal electrodes. [1][2][3][4][5][6] The possible mechanism responsible for the SBH tuning is still a matter of discussion and conflicting models are reported. The essential crux in question appears to be an indistinct role of the silicon interlayer; it either decreases the density of interface states ͑thus unpins the Fermi level 1,2 ͒ or its bulk-derived properties drive the Fermi level at the Si/GaAs interface to a new position.…”