The Impact of an Ultrathin Y₂O₃Layer on GeO₂Passivation in Ge MOS Gate Stacks

Suppression of GeOx interfacial layer and enhancement of the electrical performance of the high-K gate stack by the atomic-layer-deposited AlN buffer layer on Ge metal-oxide-semiconductor devices

“…[1][2][3][4] However, the lack of high-quality and thermodynamically stable gate dielectrics is a major problem in implementing Ge and III-V semiconductors as the channel materials. [5][6][7][8][9][10] For Ge, it is difficult to suppress the formation of a low-K germanium oxide (GeO x ) interfacial layer (IL) at the high-K and Ge interface, which limits the minimum achievable equivalent oxide thickness. 11,12 In contrast to the SiO 2 /Si system, interfacial GeO x has been reported to be thermodynamically unstable.…”

“…13,14 Many methods have been used to passivate the defects and achieve a stable high-K/Ge interface, such as the use of ultrathin Si, high-quality Ge oxides, and rare-earth oxides (Y 2 O 3 , SmGeO x , etc.). 6,[15][16][17] One of the most widely used methods is the insertion of an Al 2 O 3 buffer layer between the high-K oxide and Ge because of the high bandgap and good thermal stability of Al 2 O 3 . 18,19 Besides, it has been reported that nitrogen incorporation into GeO x yields an improvement in the thermal stability and the dielectric constant.…”

High Mobility Ge pMOSFETs with ZrO2 Dielectric: Impacts of Post Annealing

“…A high-quality gate dielectric and effective passivation of Ge surface are the keys to realizing the superior effective carrier mobility ( μ eff ) and high drive current in Ge transistor [4–7]. Several high-κ materials such as HfO 2 [8], ZrO 2 [7, 9], La 2 O 3 [10], and Y 2 O 3 [11] have been studied as the alternative gate dielectrics for Ge p-type metal-oxide-semiconductor field-effect transistors (pMOSFETs) to achieve capacitance equivalent thickness (CET) scalability toward sub-1 nm. Among these, ZrO 2 dielectric has attracted most attention due to the much higher κ value [12, 13] and the better interfacial quality [14] compared to the Hf-based ones.…”

Improvements on the Interfacial Properties of High-k/Ge MIS Structures by Inserting a La2O3 Passivation Layer

“…Recently, it has been reported that rare earth oxides (REOs; i.e., Y 2 O 3 , CeO 2 , Sm 2 O 3 , and La 2 O 3 ) show high affinity for Ge atoms. That is, the strong reaction between REOs and Ge substrates leads to the catalytic oxidation of Ge, which results in the spontaneous formation of stable interfacial layers [13,14,15,16]. Amongst the REOs, due to their large dielectric constant and high band offset relative to Ge, La-based oxides are considered as one kind of promising alternative gate dielectrics in Ge-based MIS devices, which can achieve more aggressive equivalent oxide thickness (EOT) scaling [17,18].…”