Barrios, P.J.

Chowdhury, U.

Dupuis, R.D.

Hall, D.C.

Jasinski, J.B.

Kosel, T.H.

Liliental-Weber, Z.

Snider, G.L.

eScholarship - University of California

Lawrence Berkeley National LaboratoryRecent WorkTitleProperties of InAlP native oxides supporting MOS inversion-layer behaviorPermalinkhttps://escholarship.org/uc/item/7k29t0s8AuthorsBarrios, P.J.Hall, D.C.Chowdhury, U.et al.Publication Date2002-04-08eScholarship.org Powered by the California Digital LibraryUniversity of CaliforniaProperties of InAlP Native Oxides Supporting MOS Inversion-layer BehaviorP. J. Barrios,2 D. C. Hall,1 U. Chowdhury,3 R. D. Dupuis,3 J. B. Jasinski,4 Z. Liliental-Weber,4 T. H. Kosel,1 and G. L. Snider1 1University of Notre Dame, Dept. of Elecl. Eng., 260 Fitzpatrick Hall, Notre Dame, IN46556-5637 USA 2Now at National Research Council, Inst. for Microstructural Sciences, Ottawa, OntarioK1A 0R6 Canada 3The University of Texas at Austin, Microelectronics Rsrch. Ctr., PRC/MER-R9900,Austin, TX 78712 USA 4Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720 USAGaAs remains the most widely employed semiconductor for high-speed electronicapplications due to its crystal growth and processing maturity, and wide array ofcompatible, high electron mobility alloys of varying bandgap that can be grownepitaxially on its surface.  However, its incapacity to produce a native oxide of electricalcharacteristics similar to those of SiO2 on Si, has hindered its development in low-powerapplications.  Native oxides produced by the wet oxidation of epitaxial AlGaAs sufferfrom high leakage currents and As-related traps.  However, wet thermal native oxides ofAs-free In0.485Al 0.515P (lattice matched to GaAs) have been found to have excellentinsulating properties and may provide a viable oxide for III-V MOS applications.[1],[2]Two ~63 nm thick InAlP films, both with and without a 10 nm InGaP oxidation barrier,are grown by MOCVD on GaAs and surface-oxidized in water vapor (500 °C, 30-120min).  Fully oxidized (60 min), the films expand to 110 nm as revealed by transmissionelectron microscopy (TEM) and variable-angle spectroscopic ellipsometry (VASE)measurements.  Upon etching the oxides back to 49 nm for more direct comparison tooxidized AlGaAs samples, the leakage increases only slightly (2-3X) to ~6e-10 A/cm2 at5 V, still about 4 orders of magnitude less than our best leakage current in comparablethickness Al0.98Ga0.02As native oxides. Breakdown fields for these thin InAlP nativeoxides are in the 5 MV/cm range – more than 1.5 times higher than our AlGaAs oxides,and similar to those reported for Ga2O3(Gd2O3).[3] However, leakage was found toincrease significantly (to ~1.6e-2 A/cm2) when the film was etched to ~25 nm, exposing aregion which TEM imaging shows is filled with higher density precipitates.We have reported[2] that high-frequency (1 MHz) and quasi-static C-V measurements onilluminated InAlP oxide MOS capacitors show clear signs of an inversion layer,dependent on oxidation time (optimal at 60 min), suggesting a relatively clean interfaceand possibly unpinned Fermi level. TEM studies show the oxidation front stoppingwithin the InAlP just above the underlying interface in samples with or without an InGaPbarrier, providing a clean semiconductor heterointerface at which the inversion layerlikely forms. While unprotected GaAs oxidizes relatively quickly at these temperatures,its oxidation appears to be prevented (or greatly retarded) by the InAlP oxide “cap”.  Incontrast, the porous AlGaAs native oxides do not prevent GaAs oxidation.  The InAlPoxide thus appears sufficiently dense (consistent with the observed diffusion-limitedoxidation kinetics) to prevent the outdiffusion of Ga and As, as necessary for GaAsoxidation.  Finally, TEM imaging shows that InAlP oxides on structures with the InGaPbarrier layer have much smoother interfaces and greater thickness uniformity.This work was supported by AFOSR.[1] Adrian L. Holmes, Ph.D. Dissertation, The U. of Texas at Austin, December 1999.[2] P. J. Barrios, D. C. Hall, G. L. Snider, T. H. Kosel, U. Chowdhury and R. D. Dupuis,in State-of-the-Art Program on Compound Semiconductors (SOTAPOCS XXXIV), 199thMeeting of The Electrochemical Society (Washington, DC, March 25 - 30, 2001).[3] M. Hong, J. Kwo, A. R. Kortan, J. P. Mannaerts, and A. M. Sergent, Science 283,1897 (1999).

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Properties of InAlP native oxides supporting MOS inversion-layer behavior

Properties of InAlP native oxides supporting MOS inversion-layer behavior

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