Surface orientation dependence of interface properties of GeO2/Ge metal-oxide-semiconductor structures fabricated by thermal oxidation

Abstract

We have fabricated GeO2/Ge interfaces on (100), (110), and (111) orientation substrates by direct thermal oxidation. The x-ray photoelectron spectroscopy analyses suggest that the Ge oxides are composed of GeO2 and have almost the same interfacial structure, independent of the surface orientations. The gate current conduction mechanism through the GeO2/Ge metal-oxide-semiconductor structure is dominated by Fowler–Nordheim tunneling. In addition, the barrier height between Ge and GeO2 is evaluated to be 1.2–1.4 eV. In interface trap density (Dit) measurement by using the low temperature conductance method, the amount of Dit in the conduction band side is also almost the same, while Dit in the valence band side is lowest for the (111) surface. Minimum detectable Dit is lower than 1×1011 eV−1 cm2 for all the orientations. These surface orientation dependences of the GeO2/Ge interface properties are quite different from those of the SiO2/Si interface.

HfO2/GeO N /Ge gate stacks with sub-nanometer capacitance equivalent thickness and low interface trap density by in situ NH3 plasma pretreatment

“…Fortunately, some methods to passivate the Ge interface have already been reported, such as the introduction of SiO 2 /Si [5], GeO 2 [6,7], GeO x N y [8,9], and rare earth oxides [10] as the interfacial control layer between Ge substrate and high-k layer. Although experimental and theoretical studies have proven good electrical properties of thermally grown GeO 2 /Ge interfaces, which exhibit a low D it of less than the mid 10 11 cm −2 eV −1 without any defect termination techniques [11][12][13]. However, the dielectric constant of GeO 2 is low (k = 6), which hinders the aggressive device scale [14].…”

Growth promotion of Al-induced crystallized Ge films on insulators by insertion of a Ge membrane below the Al layer

“…Germanium is useful for fabricating high-speed metal-oxide-semiconductor 38 field-effect transistors (MOSFETs) and high-efficiency tandem solar cells [1][2][3] prepared on the a-Ge membranes and then exposed to air for 10 minutes to form native 78 Al oxide layers (AlOx). After that, second a-Ge layers were prepared on the AlOx layers.…”

Plasma-oxidation of Ge(100) surfaces using dielectric barrier discharge investigated by metastable induced electron spectroscopy, ultraviolet photoelectron spectroscopy, and x-ray photoelectron spectroscopy

“…The film formation and the GeO 2 /Ge interface structure are the same for the surface orientations Ge(100), (110), and (111). 24 Another possibility for oxide formation is the growth of GeO 2 layers by atomic layer deposition typically at temperatures between 350 and 450 C in an oxygen atmosphere. 1,4 All procedures described so far deliver well defined GeO 2 layers grown up to sufficient thicknesses and very low interface defect densities.…”