Growth and Characterization of InSb films on Si (001)

ABSTRACTThe 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. In the current work we describe the growth of InSb on Si (001) 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 width.Samples were grown using molecular-beam epitaxy in a Riber-Compact 21T system. Antimony was supplied with a Veeco valved cracker cell. Vicinal Si(001) substrates offcut by 4º toward [110] were prepared by repeated oxidation and oxide-removal and then loaded into the MBE system. After the substrate temperature had been increased to about 820ºC, the surface shows a clear 24 reconstruction and appears to be free of oxide. This reconstruction remains until the substrate temperature reaches 1015ºC, at which temperature a 21 appears, indicating a dominance of double-height steps. After allowing the substrate to cool to the intended growth temperature for InSb, it is exposed to cracked Sb, resulting in the surface going from 21 to 11. This 11 reconstruction remains throughout the subsequent InSb deposition. InSb was deposited with a Sb/In flux ratio of about 5 and a growth rate of 0.2 nm/s. We have investigated growth temperatures between 300 and 420ºC for growth. To prevent the formation of the defects we introduced in some samples GaSb/AlSb supperlattice buffer layer. The best structural quality has been achieved at a growth temperature of 420ºC using GaSb/AlSb supperlattice buffer layer, resulting in our best electron mobility of 2.6104 cm2/Vs for a 2m film at room temperature. The samples grown at 420°C have the narrowest x-ray rocking curve width (FWHM of about 950 arcsec). Deep level noise spectra indicate the existence of the deep levels. The sample with the best crystal quality and highest mobility has the lowest traps. The deep levels have a temperature dependent behavior.