Interfacial, Electrical, and Band Alignment Characteristics of HfO2/Ge Stacks with In Situ-Formed SiO2 Interlayer by Plasma-Enhanced Atomic Layer Deposition

Abstract

In situ-formed SiO2 was introduced into HfO2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO2/SiO2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation. In addition, it can also suppress the GeO2 degradation. The electrical measurements show that capacitance equivalent thickness of 1.53 nm and a leakage current density of 2.1 × 10−3 A/cm2 at gate bias of Vfb + 1 V was obtained for the annealed sample. The conduction (valence) band offsets at the HfO2/SiO2/Ge interface with and without PDA are found to be 2.24 (2.69) and 2.48 (2.45) eV, respectively. These results indicate that in situ PEALD SiO2 may be a promising interfacial control layer for the realization of high-quality Ge-based transistor devices. Moreover, it can be demonstrated that PEALD is a much more powerful technology for ultrathin interfacial control layer deposition than MOCVD.

Formation and characterization of holmium oxide on germanium‐based metal‐oxide‐semiconductor capacitor

“…A systematic study of XRD patterns was conducted to get detailed insight into the crystal orientation and structure of the fabricated gate stack. Figure 1 Furthermore, according to the XRD pattern, it is noticed that peak intensity of c-Ho 2 O 3 at 29.16 (222), 59.08 (631), and 48.20 (440) increases when the oxidation/nitridation duration extended from 5 minutes to 10 and 15 minutes but gradually decreasing from 10 to 20 minutes as shown in Figure 2. It is apparent that 10 minutes exhibits the highest Ho 2 O 3 peak intensity followed by 15 and 5 minutes samples and 20 minutes sample exhibits the lowest intensity.…”

“…The conventional tailed region noticed at low binding energy site of VB spectra is being considered as Ge substrate signal. The reference position of VB edge, E v (Ge) was considered at 0.10 eV, obtained from the reported literature 59 and was assumed to be constant for various oxidation/nitridation duration. The VB edge, E v of Ho 2 O 3 /IL was approximated by the linear extrapolation intercept of the maximum negative slope leading edge in VB spectra with the minimum edge of Ge substrate baseline as demonstrated in Figure 10A.…”

Surface electronic structure of Si1−x Ge x (001)-2 × 1: a synchrotron radiation photoemission study

“…The present report suggests that the study of the SiO 2 /SiGe interface is practically an investigation of the SiO 2 /Ge interface. Recently, Cao et al have used XPS to study the HfO 2 /SiO 2 /Ge stack, 38) where the interfacial bonding is claimed to be in a Si-O-Ge fashion. Our recent publication regarding growth of thin single-crystal Si 0.7 nm thick on epi Ge(001)-2 × 1 and its oxidation reveals that SiO x (x = 1-4) readily formed on the Si surface upon annealing without involving the Si/Ge(001) interface.…”

Plasma-enhanced atomic layer deposited SiO2 enables positive thin film charge and surface recombination velocity of 1.3 cm/s on germanium

“…As discussed above the QGe/GeOx is positive. The positive QSiO2 is originated from the 3-fold bonded oxygen 26 , magnitude of which is determined by the sum of GeOx/SiO2 interface fixed charge and the SiO2 bulk charge 14,24,25,27 . The QAl2O3 is reported to be related to the trapped electrons that tunnel through the SiO2 layer and contribute to the negative charge near the SiO2/Al2O3 interface 25,28 .…”