Growth and Characterization of InSb films on Si (001)
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Growth and Characterization of InSb films on Si (001) Lien Tran, Julia Dobbert, Fariba Hatami, and W. Ted Masselink Department of Physics, Humboldt-Universität zu Berlin, Newtonstr. 15, Berlin, 12489, Germany ABSTRACT In this paper we describe the growth of InSb on Si (001) using molecular-beam epitaxy and discuss the structural and electrical properties of the resulting InSb films. The samples were characterized in terms of background electron concentration, mobility, deep level traps, Hall sensitivity, and x-ray rocking curve. We have investigated samples grown at temperatures between 300ºC and 420ºC. To prevent the formation of the defects we introduced in some samples GaSb/AlSb superlattice buffer layer. The best structural quality has been achieved at a growth temperature of 420ºC using GaSb/AlSb superlattice buffer layer, resulting in our best electron mobility of 26500 cm2/Vs for a 2µm film at room temperature. This sample has the narrowest x-ray rocking curve width. Deep level noise spectra indicate the existence of the deep levels in all samples in a temperature range of 80 to 300 K. The sample with the best crystal quality and highest mobility, however, has the lowest trap density. The deep levels have a temperature dependent behavior. INTRODUCTION The replacement of native oxides with deposited oxides in CMOS technology opens the door to replacing the Si with semiconductors without high-quality native oxides. For example, the use of InSb in logic applications could allow much lower operating voltages and power dissipation due to the InSb channels reaching saturation at significantly lower electric fields. Epitaxy of InSb onto Si could be done directly or using an intermediate layer such as GaP, GaAs, or InP. Furthermore, InSb, the narrowest bandgap III-V material, has potential applications in high speed devices, infrared (IR) detectors and magnetic sensors. Especially for IR application, InSb thin films should be grown on semi-insulating IR transparent substrates [1]. Although, there is a large lattice mismatch between GaAs and InSb (14.6%), GaAs is still an attractive substrate material due to its chemical stability and high resistivity. The epitaxial growth of InSb on GaAs substrates have been demonstrated by several groups [2-6]. Compared to the growth on GaAs, less has been reported on the heteroepitaxy of InSb on Si [7-8]. The difficulties involved in growth of high quality InSb films on Si include the large lattice mismatch (19%), the different thermal expansion coefficients (α InSb ~ 2αSi at room temperature) and antiphase domain formation due to the growth of polar semiconductor on nonpolar semiconductor. Some problems have been eliminated using tilted substrates [9], indium predeposition and the insertion of various buffer layers [10–12]. In the current paper, we describe the detailed growth of InSb on Si (001) using molecular-beam epitaxy (MBE) and discuss the structural and electrical properties of the resulting InSb films. Our results are based on X-Ray diffraction, Hall-effect m
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