Raman scattering and electrical characterization of AlGaAs/GaAs rectangular and triangular barriers grown by MOCVD

 

J. Díaz–Reyes*¹, M. Galván–Arellano² and R. Peña–Sierra²

 

¹ CIBA–IPN, Ex–Hacienda de San Juan Molino Km. 1.5, Tepetitla, Tlaxcala. 90700. México. *e–mail: jdiazr2001@yahoo.com.

² CINVESTAV–IPN, Depto. de Ing. Eléctrica, SEES Apdo. Postal 14–740, México, D. F. 07000. México.

 

Recibido: 20 de octubre de 2009.
Aceptado: 20 de enero de 2010.

 

Abstract

It presents the structural and electrical characterization of rectangular and triangular barriers based on Al_xGa_1–xAs/GaAs heterostructures grown in a metallic–arsenic–based–MOCVD system. The gallium and aluminum precursors were the organmetallic compounds trimethylgallium and trimethylaluminum, respectively. The barriers were grown with different aluminum concentrations for varying the AlGaAs bandgap and as consequence the potential barrier height. To obtain the triangular barriers increased the Al concentration gradually each minute up to reach 40% molar fraction. Raman spectroscopy was used to the structural characterization of the barriers. Potential barrier height and carrier transport mechanism through them is obtained by the current–voltage measurements. Raman spectra of the rectangular barrier present the TO GaAs–like, LO GaAs–like and LO AlAs–like as main vibrational modes. As the growth temperature is increased the layers compensation decreases but the Raman spectra show that the layers become more defective. The triangular barriers Raman spectra presented the same vibrational modes. As the Al concentration is increased the Triangular barriers phononic bands shifted slightly to lower wavenumbers and are broader compared with the phononic bands of the rectangular barriers.

Keywords: Semiconductors III–V; GaAs; Barrier height; Raman spectroscopy; MOCVD.

 

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