Ge n-MOSFETs on lightly doped substrates with high-/spl kappa/ dielectric and TaN gate

Abstract

In this letter, we report successful fabrication of Germanium n-MOSFETs on lightly doped Ge substrates with a thin HfO 2 dielectric (equivalent oxide thickness 10 8 A) andTaN gate electrode. The highest peak mobility (330 cm 2 /V s) and saturated drive current (130 A/sq at -= 1 5 V) have been demonstrated for n-channel bulk Ge MOSFETs with an ultrathin dielectric. As compared to Si control devices, 2.5 enhancement of peak mobility has been achieved. The poor performance of Ge n-MOSFET devices reported recently and its mechanism have been investigated. Impurity induced structural defects are believed to be responsible for the severe degradation.

Dangling bonds and vacancies in germanium

“…[4][5][6] The poor device performance is likely caused by the presence of defects near the semiconductor/dielectric interface, such as germanium dangling bonds (DBs) or vacancies, making the study and characterization of these defects a much needed and timely task.…”

Molecular beam epitaxy-grown Al2O3/HfO2 high-κ dielectrics for germanium

“…Feverish research efforts were carried out to identify dielectrics suitable for Ge passivation, since native oxide of Ge (GeO x ) results in poor electrical properties. Previous intense research work on Ge MOS devices has concluded that interfacial layers such as GeO x N y [1,2] or epi-Si/SiO 2 [3,4] are required for effective passivation of Ge and for preventing inter-diffusion between Ge and the subsequent deposited high-k dielectrics.…”

Electron mobility in silicon and germanium inversion layers: The role of remote phonon scattering

“…So far, the mobility in fabricated Ge MOSFETs has been disappointing [10,11], possibly due to processing issues. Hence our results set an upper limit on the mobility and comparison to fabricated Ge devices is not yet meaningful.…”