Uniformity of improved high-quality GaAs and AlGaAs epilayers and Schottky barriers prepared by molecular beam epitaxy

M. Missous*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The growth by molecular beam epitaxy (MBE) of GaAs and AlGaAs, although a well controlled process, has nevertheless suffered from poor reproducibility and uniformity across large substrates (greater than 2 inch) as would be required in practice for the fabrication of devices, the MESFET being a point in case. Recent advances in the design of MBE deposition chambers coupled with the availability of high-purity starting source materials have enabled the growth of unprecedentedly high-quality, very uniform GaAs and AlGaAs with electronic defect densities below 1014 cm-3, even for the highly reactive AlAs binary, and with a compositional uniformity for the ternary alloy (AlGaAs) of better than +or-0.5%, corresponding to temperature variations of less than 1 degrees C at 700 degrees C. The design of a new Ga hot-lip cell in the VG V90H MBE system has enabled total structural defects of less than 400 cm-2 to be routinely achieved on 2 inch substrates. The ability to deposit well characterised single-crystal Al films on GaAs and AlGaAs has also led to a new dimension in the reproducibility and control of near-ideal Schottky diodes for MESFET and HEMT applications. The advantages of such structures include uniformities of better than +or-5 meV in the barrier height across 2 inch substrates and thermal stabilities up to 500 degrees C. The practical significance of these results will be emphasised for the GaAs-AlGaAs system.

Original languageEnglish
Article number048
Pages (from-to)A249-A254
JournalSemiconductor Science and Technology
Volume7
Issue number1 A
DOIs
Publication statusPublished - 1 Dec 1992

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