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Abstract: In this paper we present the study of the S-passivation of the Ge gate stack. S-passivation was achieved by using H2S exposure on the clean Ge(100) surface. Al2O3 was deposited on the Ge/S surface by atomic layer deposition (ALD). The resulting gate stacks were analyzed chemically and electrically. We studied the influence of the ALD oxidant precursor (H2O versus O3) on the passivation behavior of the gate stack. We observe that for the same surface passivation, the interface depends largely on the oxidant precursor: H2O as a precursor results in a gate stack free of Ge-oxide and the gate stack shows low D it at the valence band edge. On the other hand, O3 as a precursor results in a thin GeO x S y interfacial layer with low D it at the mid gap and conduction band edge. [Copyright &y& Elsevier]

Abstract: A fundamental issue regarding the introduction of high-mobility Ge channels in CMOS circuits is the electrical passivation of the interface with the high-k gate dielectric. In this paper, we investigate the passivation of p-Ge(001) using molecular H2S. The modification of the semiconductor surface is monitored in situ by RHEED and the interface is characterized by XPS analyses. MOS capacitors are fabricated to extract interface state density, and finally we demonstrate the efficiency of the passivation scheme using a combination with an ultra thin Al interlayer. [Copyright &y& Elsevier]

Abstract: Photoluminescence intensity (PLI) measurements of GaAs and InGaAs thin films indicate that InGaAs might be inherently easier to passivate than GaAs. The introduction of just 15% of In leads to a reduction of the surface recombination velocity at native oxide interfaces by an order of magnitude. This is more than the effect expected by a reduced bandgap alone. The PLI method applied to thin films can also be used to determine the surface recombination velocity of other IIIV-oxide interfaces. [Copyright &y& Elsevier]

Abstract: HfTa x O y high-k dielectric layers with different compositions were deposited using ALD on 1nm SiO2 generated by ozone based cleaning of 200mm Si(100) surface. Physical characterization of blanket layers and C–V mapping demonstrates that the ALD layers have excellent uniformity and controllable compositions. The layers with a composition of HfTaO5.5 remain amorphous after annealing at 900°C. The C–V measurements of MOS capacitors show no hysteresis, negligible frequency dispersion and interfacial state density smaller than 3×1011 (cm−2 eV−1). k-value of the amorphous layers varies in the range from 20 to 25, depending on layer composition. The flat band voltage does not shift with the increase of EOT, implying that the effect of fixed charge densities in the layers is negligible. The I–V measurements show a leakage reduction comparable to that of the ALD HfO2 layers. [Copyright &y& Elsevier]

Abstract: Band gap and band offsets of hafnium and zirconium oxides were investigated on Ge substrates with a fixed Al2O3/GeO2 passivation layer. Chemical properties and band alignment with Ge were determined by X-ray photoelectron spectroscopy; characterization of structure and morphology was done using transmission electron microscopy. All samples investigated were found to be chemically suitable for Ge advanced applications and with sufficient energy barriers for holes and electrons for the use of Ge as a future channel material. [Copyright &y& Elsevier]