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The high mobility germanium (Ge) channel is considered as a strong candidate for replacing Si in pMOSFETs in the near future. It has been reported that the conventional power-law degradation kinetics of Si devices is inapplicable to Ge. In this paper, further investigation is carried out on defect energy distribution, which clearly shows that this is because the defects in GeO2/Ge and SiON/Si devices have different physical properties. The three main differences are: 1) energy alternating defects (EAD) exist in Ge devices but are insignificant in Si; 2) the distribution of as-grown hole traps has a tail in the Ge bandgap but not in Si, which plays an important role in the degradation kinetics and device lifetime prediction; and 3) EAD generation in Ge devices requires the injected charge carriers to overcome a second energy barrier, but not in Si. Taking the above differences into account, the power-law kinetics of EAD generation can be successfully restored by following a new procedure, which can assist in the Ge process/device optimization. [ABSTRACT FROM PUBLISHER]

Ge is a candidate for replacing Si, especially for pMOSFETs, because of its high hole mobility. For Si-pMOSFETs, negative-bias temperature instabilities (NBTI) limit their lifetime. There is little information available for the NBTI of Ge-pMOSFETs with Ge/GeO2/Al2O3 stack. The objective of this paper is to provide this information and compare the NBTI of Ge- and Si-pMOSFETs. New findings include: 1) the time exponent varies with stress biases/field when measured by either the conventional slow dc or pulse I-V technique, making the conventional Vg -accelerated method for predicting the lifetime of Si-pMOSFETs inapplicable to Ge-pMOSFETs used in this paper; 2) the NBTI is dominated by positive charges (PCs) in dielectric, rather than generated interface states; 3) the PC in Ge/GeO2/Al2O3 can be fully annealed at 150 ^\circC ; and 4) the defect losses reported for Si sample were not observed. For the first time, we report that the PCs in oxides on Ge and Si behave differently, and to explain the difference, an energy-switching model is proposed for hole traps in Ge-MOSEFTs: their energy levels have a spread below the edge of valence band, i.e., Ev , when neutral, lift well above Ev after charging, and return below Ev following neutralization. [ABSTRACT FROM PUBLISHER]

The high hole mobility of Ge makes it a strong candidate for end of roadmap pMOSFETs and low interface states have been achieved for the Al2O3/GeO2/Ge gate-stack. This structure, however, suffers from significant negative bias temperature instability (NBTI), dominated by positive charge (PC) in Al2O3GeO2. An in-depth understanding of the PCs will assist in the minimization of NBTI and the defect energy distribution will provide valuable information. The energy distribution also provides the effective charge density at a given surface potential, a key parameter required for simulating the impact of NBTI on device and circuit performance. For the first time, this letter reports the energy distribution of the PC in Al2O3GeO2 on Ge. It is found that the energy density of the PC has a clear peak near Ge Ec at the interface and a relatively low level between Ec and Ev. Below Ev at the interface, it increases rapidly and screens 20% of the Vg rise. [ABSTRACT FROM PUBLISHER]