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Metamorphic Te-doped Al(0.4)In(0.6)Sb/Ga(0.4)In(0.6)Sb HEMT structures for low power and high frequency applications

: Lösch, R.; Aidam, R.; Kirste, L.; Leuther, A.

Verband der Elektrotechnik, Elektronik, Informationstechnik -VDE-:
23rd International Conference on Indium Phosphide and Related Materials, IPRM 2011. Conference Proceedings : May 22 - 26, 2011, Maritim ProArte Hotel, Berlin,Germany
Berlin: VDE-Verlag, 2011
ISBN: 978-3-8007-3356-9
International Conference on Indium Phosphide and Related Materials (IPRM) <23, 2011, Berlin>
Fraunhofer IAF ()

We report on the molecular beam epitaxial growth of metamorphic AlInSb/GaInSb high-electron-mobility-transistor structures for low power, high frequency applications on 4-inch GaAs substrates. The structures con-sist of a Ga0.4In0.6Sb channel embedded in Al0.4In0.6Sb barrier layers which are grown on top of an insulating metamorphic buffer, which is based on the linear exchange of Ga versus In and a subsequent exchange of As versus Sb. Growth parameters were systematically investigated by means of HRXRD, AFM and TEM measure-ments. The beam-equivalent-pressure ratio As/Sb (~3.5) in conjunction with the substrate temperature were found to be the key parameters to get good crystalline quality, demonstrated by the presence of crosshatching, a root mean square roughness of 2.0 nm and good electrical performance. Buffer isolation is determined to be about 1M Ohm/? for optimised growth conditions. Van-der-Pauw Hall measurements at room temperature reveal electron densities of 2.2 x 1012 cm-2 in the channel at mobility values of 22.000 cm2/Vs for single-sided Te -doped samples and 5.4 x 1012 cm-2 and 17.000 cm2/Vs for double-sided Te delta-doped structures, respectively. These high sheet carrier densities combined with maintained high electron mobilities, attributed to our new sophisticated buffer design, are essential for the fabrication of high frequency, high power MMICs.